Add the simple underpinnings of a "type" system to the config file
parser.  Adding ":boolean" to a keyword will enforce boolean semantics
on the keyword's value, and will convert it to a boolean value
instead of a string when parsed.
Give the compatibility shim its own debugging flag: DEBUG_COMPATIBILITY
Add a new boolean to the voicemail config: "auto_password" that causes the
voicemail system to skip authentication if the call is coming from the owner
of the calling extension, or any one of the extensions sharing its message waiting
indicator.
Allow "ON" or "OFF" (upper, lower or mixed case) as an allowable boolean value
Convert the "many_handsets" keyword to a true boolean.
Make git ignore a personalized dialplan_config.txt file.