Turn off auto-fit on all non-Windows OSs

Auto-fit seems to work poorly on Gnome 3 (See #53). Don't know about
other DEs, and it's better to include ones that work gradually, rather
than exclude those that don't one by one.
Fix incorrect encoding on Qt 4
Fix punctuations

Fix #61
Fix "Unescaped backslashes are deprecated" warning in Qt 5
Fix some NULL-pointer guards
Fix glitch where a tiny context menu appears
Fix view-centering bug
Refactor View::mousrReleaseEvent
Add middle-click to paste
Unify toolbar label font
Remove some dead code
Fix zh_Hant declaration
Merge branch 'master' of https://github.com/uranusjr/Qelly
Merge branch 'master' into refactor