CMOC/gcc6809 support

With a few steps I added gcc6809 and CMOC to the compilers. For the
latter I wrote a simple wrapper [2] that translates command line
options. A screenshot can be found here:

http://toolshed.sourceforge.net/gcc-explorer/gcc-explorer5.png

A short write-up on how to install and run, including a small "exercise":

http://toolshed.sourceforge.net/gcc-explorer/gcc6809-tutorial

(received via email from Tormod Volden)

[2] http://toolshed.sourceforge.net/gcc-explorer/cmoc-wrapper

Start by reviewing the existing compiler integration entry points and compare them with the linked cmoc-wrapper and gcc6809 tutorial. Confirm the expected compiler commands, option translation, and installation requirements; done means gcc6809 and CMOC can be selected and used successfully in Compiler Explorer.

Written by the indexing model from the issue text.