lightr 1.7.0

Minor changes

• Errors in low-level parsers are now passed as warnings in high-level
  lr_get_XXX() functions instead of being completely silenced.

• IRR8 (irradiance files produced by AvaSoft 8) are now explicitly supported by
  lr_get_spec(). An alias has been added for the low-level parser:
  lr_parse_irr8().