Fix indentation
Avoid using a global static buffer for config loading
Search system-dependant data paths for relative hrtf table filenames
Avoid checking the hrtf config option twice
Check the hrtf config option earlier

This is to make sure it tries to find an HRTF-compatible format before reseting
the device, just like when using ALC_HRTF_SOFT.
Add a return value to FindHrtfFormat
Move the default hrtf table to an external file
Move HRTF macros and function declarations to a separate header
Revert "Apply HRTF coefficient stepping separately"

This reverts commit 25b9c3d0c15e959d544f5d0ac7ea507ea5f6d69f.

Conflicts:
	Alc/mixer_neon.c

Unfortunately this also undoes the Neon-enhanced ApplyCoeffsStep method.
Attempt to restore the Neon-enhanced ApplyCoeffsStep method

Unable to test, but it hopefully works.
Fix a config option comment
Support environment variables in the hrtf_tables config value
Expand environment variables for all config option values when loading
Don't fallback to relative filename handling if opening as absolute fails
Add an explicit cast to make Windows happy
Move OpenDataFile to helpers.c so other sources can use it
Add a note that absolute paths may be used for hrtf_tables
Use OpenDataFile to load soundfonts relative to data directories
Add back the missing PATH_MAX fallback
Move PATH_MAX fallback definitions to alMain.h