Language strings fixes. Closes #1318 #1329 #1337

The commit does the following:

 * 1318: Capitalized words of the first level menu entries. IMHO there's no need to capitalize everything.
 * 1329: Plural form for the string.

Issue 1337 is reported with three different problems:

 * First one is actually not a problem, so it is ignored.
 * The second one is what this commit "fixes" - it makes the string more understandable, inspired by the Firefox's string for data resending.
 * The third problem is not reproducible by my setup, so I propose the user open another issue with more details, so we could focus more on the problem.