pdProfiler: simplify process of saving log files

Anything that makes the class easier for me to drop-in/drop-out is
great, as it encourages me to make better use of it.

As of this commit, output files will now be automatically logged to the
program's Data/Debug folder using the report name (rather than requiring
the caller to manually supply a name).  This also spares us from
cluttering up the debug window with performance reports, unless
specifically requested.
Adjustments > Levels: fix potential DBZ error when using old macros that contain Levels commands
pdXML: fix bad typo
Macros: add failsafe detection for missing macro entries

Should never be possible, but better safe than sorry
QuickSave PNG function: add failsafe if uninitialized DIB is passed

Again, worst-case scenario failsafe
pdProfiler: add support for persistent tracking (e.g. across multiple sessions)

This commit includes a whole swath of other cool features, like tracking
historical mean, std dev, and CV for arbitrary data sets.