Support for alternate Morse code groups

[GoogleCodeExporter]

The current set is basically International morse code, cribbed from Wikipedia. 
It's set up by directly plopping elements into a map in DotDashIMEService. It 
would be nice to support alternate lists of codes. Perhaps the best way to do 
that would be by separating out the code lists into an XML file, and then 
provide a settings page where the user can select which set to use?

I've had one commenter request that the code .-..-.. for newline be added to 
the application. I indeed had this in earlier versions of the program, though I 
don't recall where I picked it up from (apparently it's known somewhere, 
because this user knew it, and I hadn't published the source code yet). Changes 
like that, adding a single code group, are a bit more complicated. For the 
exclamation mark, I simply supported both, but since the newline can cause you 
to "submit" things if you press it, it's something you don't want to press 
accidentally, so I've commented it out.

Perhaps newline, being a special case, should have a setting of its own for 
which version(s) to support. Or maybe I ought to just support both, and list 
them both on the in-app cheat sheet.

Original issue reported on code.google.com by aaronwells on 6 Apr 2012 at 2:17

[GoogleCodeExporter]

Added an option in the settings page to choose the carriage return code group, 
the options being ".-.- only", ".-.-.. only", ".-.- or .-.-..", and "none".

Maybe I should have made it custom?

Heck, you could go crazy with the custom code groups thing, and make all your 
code groups customizable, for that matter. Make a code group editor. Then, I 
guess the cheat sheet would have to become one big, long, scrollable thing, 
since you wouldn't know how many there are or what order they should be 
displayed in.

Original comment by aaronwells on 8 Apr 2012 at 8:06