Tidy Texture Console, add cache & resource wait stats, issue stats line to log on exit.

With much trial-and-error, cleaned up the banner on the texture console and made everything
mostly fit.  Added global cache read, cache write and resource wait count events to the
console display to show if cache is working.  On clean exit, emit a log line to report
stats to log file (intended for automated tests, maybe):
LLTextureFetch::endThread: CacheReads:  2618, CacheWrites:  117, ResWaits:  0, TotalHTTPReq:  117