[asterisk-dev] extra parameter for DB read function

[Julian Lyndon-Smith]

There are often times that I want to read a DB value from the dialplan, 
and if this family/key pair does not exist, set it to some default value.

for example:

1234,1 => Set(EMAILADDR=${DB(x/y)}
1234,2 => GotoIf($["${EMAILADDR}" = ""]?3:4)
1234,3 => Set(EMAILADDR=Someone at test.com)
1234,4 => NoOp(${EMAILADDR})
1234,5 => Hangup()

I have modified the db function to take an optional extra parameter to 
set if the key does not exist. So, the dialplan would now look like:

1234,1 => Set(EMAILADDR=${DB(x/y/Someone at test.com)}
1234,2 => NoOp(${EMAILADDR})
1234,3 => Hangup()

It's just a shortcut to acheive the same goal, but with less lines in 
the dialplan.

Now, I am *not* a C programmer, so I may have made some horrendous 
mistake or potential segfault, so is there someone who would look at the 
changes before I make a fool of myself and post the patch to mantis ?

Much appreciated :)

Julian