v2.1.0

This release addresses #190, #219 and #220. Also various updates to dependencies.

272549e Update to 2.1.0
caed11d [#220] Output version in help (#264)
6fa52e0 [#190] Make sure update command includes marker file (#263)
69406cb [#219] Make sure we don't bother writing files that don't need updating (#262)
ce99575 Bump eslint from 7.0.0 to 7.1.0 (#261)
2fc695f Bump rollup from 2.10.7 to 2.10.9 (#260)
4f5ba2c Bump rollup from 2.10.5 to 2.10.7 (#259)
c2e9138 Bump rollup from 2.10.4 to 2.10.5 (#258)
c579a84 Bump rollup from 2.10.3 to 2.10.4 (#257)
c374e03 Bump rollup from 2.10.2 to 2.10.3 (#253)
acd834f Bump flow-bin from 0.124.0 to 0.125.1 (#256)
b7e3946 Bump eslint-plugin-flowtype from 4.7.0 to 5.1.0 (#255)
aec0991 Bump codecov from 3.6.5 to 3.7.0 (#254)
998b998 Bump rollup from 2.10.0 to 2.10.2 (#251)
e87bdf8 Bump rollup-plugin-analyzer from 3.2.2 to 3.2.3 (#250)
7bc9380 Bump rollup from 2.9.1 to 2.10.0 (#249)
e789d3a Bump rollup from 2.8.2 to 2.9.1 (#248)
19136d0 Bump eslint from 6.8.0 to 7.0.0 (#247)
7558027 Bump rollup from 2.8.0 to 2.8.2 (#246)
842523e Bump rollup from 2.7.6 to 2.8.0 (#244)
c6735de Bump flow-bin from 0.123.0 to 0.124.0 (#245)
4ba9959 Bump jest from 26.0.0 to 26.0.1 (#242)
0d83f67 Bump babel-jest from 26.0.0 to 26.0.1 (#243)
dbc8959 Bump jest-worker from 25.5.0 to 26.0.0 (#239)
0c33eb3 [Security] Bump acorn from 7.1.0 to 7.1.1 (#241)
12d2201 Bump babel-jest from 25.5.1 to 26.0.0 (#240)
6dd463a Bump jest from 25.5.3 to 26.0.0 (#238)
856d80d Bump rollup from 2.7.5 to 2.7.6 (#237)
951c01b Bump jest from 25.5.2 to 25.5.3 (#236)
7fe6db5 Bump jest from 25.5.1 to 25.5.2 (#233)
8434e20 Bump @babel/preset-env from 7.9.5 to 7.9.6 (#234)
755ea68 Bump @babel/core from 7.9.0 to 7.9.6 (#235)
817967b Bump rollup from 2.7.3 to 2.7.5 (#232)
640962b Bump babel-jest from 25.4.0 to 25.5.1 (#230)
e02514a Bump jest from 25.4.0 to 25.5.1 (#231)
fd4d850 Bump jest-worker from 25.4.0 to 25.5.0 (#229)
0d92164 Bump rollup from 2.7.2 to 2.7.3 (#228)
1546702 Bump rollup from 2.7.1 to 2.7.2 (#227)
3cae054 Bump prettier from 2.0.4 to 2.0.5 (#226)
e1d2cf6 Bump rollup from 2.6.1 to 2.7.1 (#225)
4d6ec18 Bump babel-jest from 25.3.0 to 25.4.0 (#223)
d61f8df Bump jest-worker from 25.2.6 to 25.4.0 (#224)
139a6f4 Bump jest from 25.3.0 to 25.4.0 (#222)
169ba07 Bump flow-bin from 0.122.0 to 0.123.0 (#221)
76d8211 Bump rollup from 2.4.0 to 2.6.1 (#218)
dce4938 Bump rollup from 2.3.4 to 2.4.0 (#217)
cd689b3 Bump babel-jest from 25.2.6 to 25.3.0 (#216)
4cfd1a2 Bump rollup from 2.3.3 to 2.3.4 (#213)
e019bf0 Bump rollup-plugin-visualizer from 4.0.3 to 4.0.4 (#214)
453e9e4 Bump jest from 25.2.7 to 25.3.0 (#215)
19e4e61 Bump @babel/preset-env from 7.9.0 to 7.9.5 (#212)
d54da3d Bump prettier from 2.0.2 to 2.0.4 (#211)
20b7d86 Bump rollup from 2.3.2 to 2.3.3 (#210)
b7f08e8 Bump flow-bin from 0.121.0 to 0.122.0 (#209)
3a798d1 Bump jest from 25.2.6 to 25.2.7 (#208)
bfa0522 Bump rollup-plugin-visualizer from 4.0.2 to 4.0.3 (#207)
54d3fee Bump chalk from 3.0.0 to 4.0.0 (#206)
7b5aa4d Bump babel-jest from 25.2.4 to 25.2.6 (#205)
1d45f90 Bump jest from 25.2.4 to 25.2.6 (#204)
dce5624 Bump jest-worker from 25.2.1 to 25.2.6 (#203)
18c7cca Bump rollup from 2.3.1 to 2.3.2 (#202)
2070329 Bump rollup-plugin-visualizer from 4.0.1 to 4.0.2 (#201)
620b325 Bump rollup from 2.3.0 to 2.3.1 (#200)
bf30dc5 Bump rollup from 2.2.0 to 2.3.0 (#199)
28d2a2d Bump jest from 25.2.3 to 25.2.4 (#198)
1b81fa3 Bump babel-jest from 25.2.3 to 25.2.4 (#197)
48a4f79 Bump rollup-plugin-visualizer from 3.3.2 to 4.0.1 (#196)
5a32619 Bump babel-jest from 25.2.1 to 25.2.3 (#195)
6f4d184 Bump jest from 25.2.2 to 25.2.3 (#194)
a780f35 Bump jest from 25.1.0 to 25.2.2 (#192)
97cebd6 Bump babel-jest from 25.1.0 to 25.2.1 (#193)
f3b8c5b Bump jest-worker from 25.1.0 to 25.2.1 (#191)
02a0b72 Bump prettier from 2.0.1 to 2.0.2 (#189)
ade609b Bump rollup from 2.1.0 to 2.2.0 (#188)
ac89471 Bump eslint-plugin-flowtype from 4.6.0 to 4.7.0 (#187)
a90ce47 Bump @babel/preset-env from 7.8.7 to 7.9.0 (#185)
2995c9a Bump prettier from 1.19.1 to 2.0.1 (#183)
85f4114 Bump @babel/core from 7.8.7 to 7.9.0 (#184)
aa64166 Bump @babel/register from 7.8.6 to 7.9.0 (#186)
dd71b5b Bump @babel/preset-flow from 7.8.3 to 7.9.0 (#182)
bdfafef Bump flow-bin from 0.120.1 to 0.121.0 (#181)
8c4e40e Bump flow-typed from 3.0.0 to 3.1.0 (#180)
ea028de Bump rollup from 2.0.6 to 2.1.0 (#179)
b43678b Bump rollup from 1.32.1 to 2.0.6 (#178)
b5b5e4c Bump rollup-plugin-visualizer from 3.3.1 to 3.3.2 (#176)
7273dbe Bump rollup-plugin-babel-minify from 9.1.1 to 10.0.0 (#177)
50cb4ed [Security] Bump acorn from 6.3.0 to 6.4.1 (#175)
50d05bb Bump minimist from 1.2.4 to 1.2.5 (#174)
cd5dc58 Bump minimist from 1.2.3 to 1.2.4 (#173)
0d484c0 Bump minimist from 1.2.0 to 1.2.3 (#172)
12aa480 Bump rollup-plugin-babel from 4.3.3 to 4.4.0 (#171)
010fdc9 Bump flow-bin from 0.119.1 to 0.120.1 (#170)
d891852 Bump rollup from 1.32.0 to 1.32.1 (#169)
1b738cb Bump @babel/preset-env from 7.8.6 to 7.8.7 (#168)
935a7b9 Bump @babel/core from 7.8.6 to 7.8.7 (#167)
aabeb17 Bump rollup from 1.31.1 to 1.32.0 (#166)
89dded3 Bump @babel/preset-env from 7.8.4 to 7.8.6 (#164)
70e212f Bump @babel/register from 7.8.3 to 7.8.6 (#163)
304e30d Bump @babel/core from 7.8.4 to 7.8.6 (#165)
d43d15d Bump flow-bin from 0.119.0 to 0.119.1 (#162)
f736c4d Bump babel-eslint from 10.0.3 to 10.1.0 (#161)
b4a0cff Bump flow-bin from 0.118.0 to 0.119.0 (#159)
488744d Bump fast-glob from 3.2.1 to 3.2.2 (#160)
cc0f691 Bump flow-typed from 2.6.2 to 3.0.0 (#157)
ca0f5c9 Bump fast-glob from 3.1.1 to 3.2.1 (#158)
e0d5db8 Bump ancesdir from 1.1.1 to 2.0.0 (#156)