Make function snippets more sensible

- The snippet for a short function now actually outputs short boilerplate without useless cruft, and the tab trigger for the short function is short.
- The snippet for the full function boilerplate that you would put at the top of a file matches MATLAB's documentation-in-comments a bit better, but not perfectly, because if we all emulated MATLAB perfectly the world would explode, and it's more important to be able to read the comments in the source code than for MATLAB to be able to read the comments in the source code. Also the tab trigger is longer, as is proper. Also got rid of stupid copyright cruft.
Update URL used for documentation lookup
Add method to spawn and send commands to a MATLAB process

There are two new bundle items: The first spawns a MATLAB process in Terminal and the second sends commands to the previously spawned process in Terminal.
Macros for moving to next and previous cells
Add macro to execute the current cell in MATLAB

Needs more work, currently it will actually select the entire cell instead of leaving the cursor at its current location; if you run the macro twice in a row it will move to the next cell instead of executing the current cell twice. Probably needs to be written as an actual command.

The execute command's script has been moved into a stand alone script so it can be used in this command as well.
Cell titles now appear in the symbol list
Made num2str command simpler
Change clear snippet shortcut to `clear`

Also remove duplicate clear snippet without as much functionality.
Add for loop with cell strings snippet (fors⇥)
Removed GPL, BSD, and revisions snippets

These aren't specific to MATLAB; ought to be in Source bundle or something
Have function snippet use filename for the function name
Removed everything to do with comment manipulation

Some of this is broken in TM2 and maybe not worth fixing, and probably it's better to have comments handled generally by Source and so on.
Remove duplicate switch snippet
Cleanup info.plist and reorganize menu layout
Add .m extension to Matlab and Octave grammars