Launchpad automatic translations update.
Use Meanwhile from MSYS2 in Windows build.

The Sametime protocol is now avaialble for 64-bit. This also fixes a problem where 64-bit debug symbols included 32-bit Meanwhile.
Add user plugin directories for 32 and 64-bit.

In addition to .purple/plugins, the following directories are also added to plugin path when the corresponding bitness is detected:

* .purple/plugins/x64, for 64-bit.
* .purple/plugins/x86, for 32-bit.
Merge translations.
Fix Enchant libraries in Windows build.

* The missing libstdc++ and Hunspell dlls are now added to installation.
* The Ispell and MySpell dlls are now explicitly added to installation.