Fixed SIP time outs being directed to the same pool thread for a given connection.
Allowed TTS cache directory to be set in VXML interpreter.
Added missing mutex when setting TTS cache in VXML.
Fixed VXML cache files, cannot use base 64 character set in a file name, use hex like before, even if longer.
Normalised various errors on sending UDP (ICMP response) to sue new PChannel::Unavailable. Also cleaned up a number of other places where errno used directly rather than normalised PChannel::Errors enumeration.
Fixed GNU compiler warning.
Fixed getting correct errno for UDP sockets, via recv error queue, at correct time and thus correctly normalise it.
Fixed extraneous @ in URI which has username and no hostname.
Update symbols
Update symbols
Update symbols
Added preset VXML variables for script URI and script directoryi, where relevant. This allows a script to access resource (WAV files etc) relative to itself.

Also fixed incorrect setting PURL from PFilePath, had missing "file" scheme in output.
Fixed VXML <record> operation. Also added ability to set directory into which recorded WAV files are stored.
Fixed close of VXML recorded file after completion of recording.
Make make a little quieter
Update symbols
Update release version number to 2.12.3
Update version number for beta v2.12.4
Back ported changes to Windows configure from trunk so when next forward port, the binary can also be merged without causing immense confusion.
Fixed handling of variable substitution in Windows configure. If not defined should be empty string, not left as the ${blah}. As often happens fixing one bug shows up another.