Fix OS X keymaps

9 conflicts:

Important ones for really used commands:
	Conflict in ctrl+shift+up ('select_lines' vs 'headline_move')
		changed -> alt+shift+up (also, ctrl+up -> alt+up)
	Conflict in ctrl+shift+down ('select_lines' vs 'headline_move')
		changed -> alt+shift+down (also, ctrl+down -> alt+down)
	Conflict in shift+tab ('prev_field' vs 'smart_folding')
		changed -> alt+tab
	Conflict in super+shift+f ('show_panel' vs 'magic_footnotes')
		changed -> alt+shift+f

Less important or desired (not changed):
	Conflict in tab ('commit_completion' vs 'smart_header')
	Conflict in super+shift+b ('build' vs 'strongemphasis')
	Conflict in super+shift+i ('show_panel' vs 'emphasis')
	Conflict in super+shift+t ('reopen_last_file' vs 'merge_cells_left')
	Conflict in enter ('hide_panel' vs 'smart_list')
is_enabled() in Sublime Text 3 needs to return a boolean
SuroundCommand does the inverse operation if executed twice in the same selection
StrongEmphasisCommand is named wrong as it's referenced as 'strongemphasis' in the keymaps. Renamed to StrongemphasisCommand
Merge pull request #55 from Kronuz/is_enabled-fix

is_enabled() in Sublime Text 3 needs to return a boolean
Merge pull request #57 from Kronuz/better-surround

SuroundCommand inverse operation
Merge pull request #56 from Kronuz/strongemphasis-fix

StrongEmphasisCommand is named wrong as it's referenced as 'strongemphas...
super+shift+i was wrongly changed in my previous commit
Remove print from SurroundCommand
Merge pull request #59 from Kronuz/better-surround

Remove print from SurroundCommand
README updated for OS X keymaps
Merge pull request #58 from Kronuz/osx-conflicts

Fix OS X keymaps
Tab Autocompletion not breaking regular tab for many cases (including multiline tab)
Keymap conflicts. Also fixes #54
Merge pull request #60 from Kronuz/tab-fixes

Slightly smarter TAB autocompletion
Merge pull request #61 from Kronuz/keymap-conflicts-fix

Keymap conflicts (ctrl+up/ctrl+down -> alt+up/alt+down)
Extended list of addornments for headers added. Fixes #27
Jump and back to footnote references only when there's no selection active
Auto-pair for `, * and |. Fixes #44
Merge pull request #63 from Kronuz/references-jump

Jump to reference only when there's no selection