Removed the DNA storage for LGG lift and inverse gamma in the color balance node. These values were always calculated at execution time, so there is no need to keep them around in DNA data and no forward compatibility break either. Only reason they were stored in DNA before is that the old compositor had no other means of keeping precomputed values around for every pixel than storing the DNA node data, with new compositor this is no longer necessary (values are stored in operations).

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61160 954f8c5b-7b00-dc11-b283-0030488c597c
Fix #37333: Bad default value in Color Balance. Use independent offset/power/slope variables for the CDL mode in color balance node. This avoids stupid default values in particular for offset, which would be 1 when just using the lift value for it.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61161 954f8c5b-7b00-dc11-b283-0030488c597c
Syncing methods for Color Balance node LGG and ASC-CDL modes. The settings for either mode are converted into equivalent settings of the other. This keeps the result of both modes roughly the same and
mimics the previous behavior when settings were shared by both modes (but not equivalent).
NOTE: Due to the use of additional sRGB conversion in the LGG mode the result is not entirely accurate, this should perhaps be fixed.

Settings for each mode are kept in their own color values nevertheless, this avoids potential problems with float precision.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61162 954f8c5b-7b00-dc11-b283-0030488c597c