Logger: add a log system instead of std::cout or printf

[dabrain34]

Add a logger with level from ERROR to DEBUG

There are 2 different to call logs:

• LOG_S_DEBUG which is a log with level 4 and acts as std::cout
• LOG_DEBUG which is a log with level 4 and acts as printf("fmt\n", args);
• LOG_DEBUG_CAT which is a log with level 4 with a category as string and acts as printf("fmt\n", args);

There are 4 kind of logs:

• LOG_DEBUG
• LOG_INFO
• LOG_WARN
• LOG_ERROR

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[dabrain34]

@zlatinski

[ceyusa]

IMO loglevel parameter overlaps with verbose one. Perhaps verbose should just enable loglevel to debug, and remove the if (verbose)s

besides that LGTM

[ceyusa]

lgtm

[dabrain34]

@zlatinski are you okay to merge this now ?

[zlatinski]

I'm okay with this change, but I would like to ask you to wait until we merge VP9 and Intra refresh changes, please.