Windows support

[AngeloFrangione]

Using meson cross files and mingw

Some resources:

• https://thiblahute.github.io/jpakkane.github.io/Cross-compilation.html
• https://mesonbuild.com/Cross-compilation.html

issues:

• thumbnailer only works with elevated command prompt.
• sqlite3_last_insert_rowid returns 0 -> the function was called to lately
• make tests work with wine

functionalities:

• make a windows build in travisCI requires: make tests work with wine
• script that copy the dll files from the subprojects to the build folder