Solves linear programs with Clp', the simplex and interior point code of the COIN-OR project <https://github.com/coin-or/Clp>. Provides a one-call solver interface for dense and sparse constraint matrices, and complete low level bindings to the Clp callable library covering problem construction, warm starts, presolve options, basis access and MPS files. A compatibility layer reproduces the interface of the archived clpAPI package so that existing code keeps working. Clp itself is not bundled and must be installed on the system; the Rtools toolchain supplies it on Windows', from Rtools 4.3 on.