Change in cmake: When BUILDTYPE is not defined in vf_add_library(), a library is build regarding the CMAKE_BUILDY_TYPE.

Changed typedefs to using.

Add msvc warning level W4 and removed most of the warnings. Some of the warnings are suppressed (see MSVC.cmake)

Update cmake to dev version.

Move VirtualFluids header to src.
Add CI file and add files, only existing in the open source version.

Remove the old write/read functions.

Warning: [-Wbackslash-newline-escape]
https://stackoverflow.com/questions/31673945/clang-backslash-and-newline-separated-by-space-in-single-line-comment

Moved numers/geomtry3d to /geometry3d.