Changes

• The Compiler is no longer a fork of the PureScript compiler. Instead, it works on corefn files generated by it.
  (see purs compile --help)
• Simplified runtime. The only automatic memory management available to generated code is reference counting via std::shared_ptr. Note that foreign code can use any type of memory management available to C/C++.
• Foreign function interface (FFI) imports/exports are now more similar to their JavaScript counterparts (notes and examples), including generally requiring manual currying.