avoid updating existing libmruby.a to avoid problems on low time resolution file systems; close #136

Changed test target for Math module in order to support fuzzy checking

Add Tests for Math, Integer, Numeric and Array

Added some tests for trig functions in Math module. Also, tests are made against a tolerance on Floats

Re-added Math functions missing under MSVC, with custom implementations

Avoid "may be used uninitialized in this function" warning.

Remove unused static functions

Test Improvement

Re-added Math finctions not supported under MSVC, and added preprocessor directives to support these functions under MSVC too

Math MSVC

move declaration in the middle
no signbit