Default to sRGB colors for CSI RGB values.

- By default consider CSI 24-bit RGB values to be display independent
  sRGB colors.
- Add an advanced option to disable this and consider the values to
  be calibrated to the given display that iTerm2 is running on.
Add proper lookups for § and ± in key-bindings stringification

The (B) and (Z) models listed at
http://support.apple.com/kb/HT2841?viewlocale=en_GB have these keys
where the tilde/backtick key goes, but appear as '⌘ Hex Code 0xa7' in
the Keys prefs fields.
add comment about colorspace
Merge branch 'master' into sRGB
Initial impl
The basics are there
Working pretty well
Simplify paste submenu
In decent condition it seems
Refactor
Save tab transform setting properly
Use iTermPreferences for user defaults
When pasting a string with tabs, show just one alert that includes an accessory for picking the tabstop size
Move the guts of paste special into its own view
Refactored
Add key binding action for paste from selection
Simplify menu
Add back paste file with b64
Pass font for profile list view to profile tag view
Loosen up spacing in toolbelt and profile list table views.