Merge branch 'hotfix/v2.1.2'
Remove hard-coded paths in build utilities.
Add Blender template to build scripts.
First working implementation of Blender template
Various fixes to get import working regardless of Blender's Context.
Scale strength values of various lamp types.
Add basic error of sIBL file contents.
Fix copy paste error in map creation logic.
Hookup drivers to rotate environment maps.
More informative error messages.
Fix real time background rotation bug with ugly hack and update known
issues.
Fix anti-rotation bug with world texture.
Improve cleanup of existing sIBL data blocks on import.
Refactor data block handling.

This should fix various bugs related to multiple scenes in the same
file and other reuses of data blocks.
Improve output script comments.
Change copyrights dates.
Update definitions and methods docstrings.
Update docstrings parameters.
Implement "foundations.parsers.SectionsFileParser.parse" method changes.
Ensure directional light position is correct in "Maya_Arnold_Standard" and "Maya_Arnold_Dome_Light" templates.

Closes kelsolaar/sIBL_GUI#203.