Do not stack allocate potentially large buffer

Also test that each system function used actually succeeds.
Increase the number of tests for sanitizing UTF-8

Also harmonize the formatting of the existing tests.
Tighter code for removing malformed UTF-8 sequences
Don’t use -KU with ruby as it logs a warning with ruby 2.0
Sanitize output from TextMate.system()

Since the API specifies an NSString we must expect valid UTF-8.
Update HTML tool tips (font and WebView cache/plug-in settings)
Disable WebView plug-ins and page cache for about window