Remove test file on test completion. Reorder test #4 and #6 so tests are sorted on running time asc.
Statically link libgcc and libstc++ on MinGW so that the test executable can be run from outsite Qt Creator
On MinGW c++11 string conversion functions are deactivated because of a bug. This commit works around the issue by using a replacement for std::stod if compiling on MinGW
Merge branch 'development' of https://github.com/bgrimstad/multivariate-splines into development