Fix compilation under MacOS
Fix localization files' installation on Linux/MacOS
Use $PREFIX/share/goldendict for locale files per Linux conventions

There is no need to use $PREFIX/share/*apps*/goldendict.
Linux: Better detection of installation prefix

1. qmake PREFIX=/usr

or

2. PREFIX=/usr qmake

or

3. export PREFIX=/usr; qmake

All should work.

Previously, the most typical #1 was not working.
Updated French translation - fixed typos
Merge pull request #373 from virtualtam/master

Updated French translation - fixed typos
MDict: Fixed truncation for ASCII characters(0x20~0x30) in image urls.
Update simplified chinese translation
Adjust fonts for some styles: Modern, Lingoes, Lingoes-Blue