v0.0.2: Do not export all functions (#1)
`get_master_elements`, `add_master_elements!`, `get_slave_elements`, `add_slave_elements!` are dispatched from `FEMBase.jl` to avoid conflicts with other contact packages.
`get_master_elements`, `add_master_elements!`, `get_slave_elements`, `add_slave_elements!` are dispatched from `FEMBase.jl` to avoid conflicts with other contact packages.