Remove some unused typedefs
Read the right command line arguments in h264dec.cpp

pArgV[i++] evalates to the same string as cmd (which is
pArgV[i]); we need to increment i before indexing into
pArgV again.
Allow setting the trace level before initializing the encoder
Actually set the trace level in the encoder console app
Add a decoder option for setting the trace level
Set the trace level in the decoder console app via a proper option
Don't treat log levels as a bitmask

All use of log levels in the library just do a numerical
greater-than comparison between the set log level and the
level of the current message.
Remove WelsStderrSetTraceLevel

The logging level is checked in welsCodecTrace anyway.

Previously, error logging wasn't ever shown if the trace
level was set to WELS_LOG_ERROR (as it was by default),
since welsStderrLevelTrace required the message level to
be strictly lower than the trace level.
Remove the unused level parameter to welsStderrLevelTrace
Change CM_WELS_TRACE to take a plain string, not a format and variadic arguments

The format string was always "%s" anyway.
Only keep one single trace function pointer in welsCodecTrace
Add a log context to the encoder and decoder contexts

This will allow setting non-global logging callbacks, that
are different for each encoder or decoder instance.
Expose a SLogContext from welsCodecTrace
Set and use a proper log context in the encoder
Set a log context in the decoder
Remove the global log callback function

Now all logging should use a non-null log context, allowing to
pass the messages to the right recipient.
Don't use global variables in welsCodecTrace

This allows actually honoring the requested log level
properly if there are multiple codec instances within
the same process.
Add a method for overriding the logging function in welsCodecTrace
Integrate the lone function from logging.cpp into welsCodecTrace.cpp
Add public options for setting a log callback