Unify logging

[tehKaiN]

• Currently there is game.log and memory.log. Having mem logged in separate file makes it hard to determine where and when specifically given alloc is taking place.
• To unify it into single file, we need something to differentiate mem and other stuff in clean and filterable/searchable way (as easy as ctrl+f). Also, game logging should be distinct from ACE stuff, but still in same file.
• We lack standard means to print warnings and errors. Currently I mostly use WARN: and ERR: prefixes, but some messages aren't still conforming to this. When other contributions arrive, it's going to be even bigger mess. Having fns like logErr, logWarn and logInfo might be a good idea.
• Log categories could be mutable (as in mute) so that reading logs would be easier. But it's something that can be bypassed by filtering.
• Also, logs should have no footprint on release builds and be non-existent there.

Any ideas?

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I've started doing this but needs further work, I think

• [x] move memory and general logging to same output
• [x] add ability to output to file or WinUAE debug console
• [ ] add consistent log message types (warning, error, info, etc.)

[tehKaiN]

the most scalable approach would be having log fn such as logWrite(szType, szMsg), but there is a consistency problem with szType categories - easy for typos. We could tackle it by enforcing codestyle for using preprocessor-defined strings as first arg.