Changes made in BSEffectShaderProperty:
1. Changed "Texture Clamp Mode" storage type from uint to byte, due to Skyrim's BSEffectShaderProperty, where the byte value of Texture Clamp Mode is followed by unknown non-zero byte value - it caused a number shown in Texture Clamp Mode line instead of its named value. This unknown byte is mostly set to 255 but in many nifs there are other values.
2. "Emmisive Color" splitted to "Base Color" (named according to CK) and "Alpha". Now the variables 0 and 5 in "EffectShaderControlledVariable" list can be clearly named.

Added proposal of abstract object for BSShaderProperties which must not be shared (can't be "combined") for easier excluding of these properties in Nifskope's Combine Properties spell. It is named "NonSharableBSShaderProperty".

Changed Skyrim specific shader blocks (BSLightingShaderProperty, BSEffectShaderProperty, BSSkyShaderProperty, BSWaterShaderProperty) to be inherit from BSShaderProperty.

Increased niftoolsxml version to 0.7.2.0 due to changes in names in this branch.