Get selected symbol correctly when code is folded

This is related to https://github.com/omz/Dash-Plugin-for-Xcode/issues/7#issuecomment-20673109.

What happens is that if the user has code folded somewhere above the place he ALT+Clicks, the string range does not match. I think that Xcode does something funny with its string storage when it's folding code and `_temporaryLinkRanges` no longer gives the correct string ranges.

This bug only occurs on ALT+Click and not when the "Quick Help with Selected Item" menu item is called (`om_showQuickHelp:`). What I did to fix the bug was to stop swizzling `textView:didClickOnTemporaryLinkAtCharacterIndex:event:isAltEvent:` completely.

Question: did you have a reason for swizzling `textView:didClickOnTemporaryLinkAtCharacterIndex:event:isAltEvent:`? It seems to work perfectly fine without it, as in Xcode just forwards the ALT+Click to `om_showQuickHelp:`.