implemented contracts for constructor and destructor which check class invariants on exit and enter respectively
fixed contract(fun) and implemented contract(meth)
moved implementation into contract::detail namespace
user settable contract violation handler callback
added __ to implementation macros to avoid conflicts
Merge branch 'feature/contract-violation-handler' into develop
removed outdated files, gave new source files better names
moved the implementation into detail/imp.hpp header
Merge branch 'feature/source-refactor' into develop
added an optional message parameter to contract macros
added copyright/license to source files
added version header file
bumped the version to 0.1.0
Merge branch 'release/0.1.0'