2.14.4 Fixed compile errors and warnings on MSVC.

Currently source code of 7kaa v2.14.4 contains compile warnings and
errors, such implicit casts, incorrect return types, unused variables,
etc.

This commit updates to 2.14.4 and includes .sln files for building in
Microsoft Visual Studio. Includes should be placed in a folder names
'include' together with 7kaa.