Regenerate all Czech .strings preferences files

for pref in General Appearance Syncing Advanced; do ibtool --export-strings-file ${pref}PreferencesView.strings ${pref}PreferencesView.xib; done
Translated new preferences messages into Czech
Corrected a slight error in Czech localization
Merged Czech .strings preferences into xibs

for pref in General Appearance Syncing Advanced; do ibtool --strings-file ${pref}PreferencesView.strings --write ${pref}PreferencesView.xib ../en.lproj/${pref}PreferencesView.xib; done
Merge pull request #11 from dusek/prefs-ng.cs

Update Czech localization in preferences