[mythtv] 4 digit channel support

[Chris Weiland]

Sorry if this has been mentioned already, but I still don't see this
supported in 0.24 and I'm getting tired of modifying the source code,
so I might as well try to get this worked into the main release.

Verizon FiOS uses 4 digit channels, but the current firewire channel
changers only support 3 digits.  This has 2 problems.  First, there is
a large delay when changing to channels < 1000 because it has to time
out on the 4th digit.  Second, channels >= 1000 are inaccessible.

Implementing the 4 digit channel change is almost trivial.  I can
easily submit a patch for that.  However, hardcoding 4 digits for the
channel changer will break everyone with only 3 digits, so it has to
be a configuration option (in the capture card screen of
mythtv-setup).  That's where my expertise runs out.  I could probably
figure it out myself, but it would be a lot less painful if one of the
existing devs could handle that part.

Are there any devs willing and able to help me out on this?