Add CTCSS support, second attempt

[charlie-foxtrot]

Same changes as #366 but including unit tests

[charlie-foxtrot]

@rough316 @feelingwalnut if you could switch to this branch for testing I would appreciate it as this will be the code that merges (functionally equivalent to the other branch)

[feelingwalnut]

@rough316 @feelingwalnut if you could switch to this branch for testing I would appreciate it as this will be the code that merges (functionally equivalent to the other branch)

git checkout add_ctcss_second_attempt
or unstable
?

[charlie-foxtrot]

git fetch
git checkout add_ctcss_second_attempt

[feelingwalnut]

compiled and running.
wish there was a solution for digital code squelch.
but also wish p25 was cracked.