Modify of Num UV Sets

Changed definition of "Num UV Sets" (for >= 10.0.1.0 only) and get rid of "BS Num UV Sets".
"Num UV Sets" defined as byte containing number of UV texture sets. Added definition of "Extra Vectors Flags" stored in byte. Only known function of that flags by that time is 4th bit representing flag for Tangents/Bitangents arrays - this is defined in bitflags type "ExtraVectorsFlags".
As there is no certainity that number of UV Sets can be stored in all 8 bits, I have left AND function on line 2731 where "arr1" is getting a number of UV Sets only from lower 6 bits (i.e. max number of UV Sets is 63). There is a note about that on line 2725 (although it is for old version 4.0.0.2).
changed type of ExtraVectorFlags component

Changed type of ExtraVectorFlags from `bitflags` to `enum`.
added billboard mode BS_ROTATE_ABOUT_UP

Added billboard mode called "BS_ROTATE_ABOUT_UP" - it has value 5. It is used in Skyrim and Fallout 3 nifs. Also works in Oblivion.
Merge pull request #23 from ttl269/feature/NiBillboardNode-update

added billboard mode BS_ROTATE_ABOUT_UP
Merge pull request #25 from ttl269/feature/Num-UV-Sets-split

Num UV Sets split
Change `Unknown Float 2` to `Refraction Strength`

See: http://niftools.sourceforge.net/forum/viewtopic.php?f=8&t=5847
Change to `LightingShaderControlledVariable` also
Merge pull request #28 from jonwd7/bslightingshaderproperty

Change `Unknown Float 2` to `Refraction Strength`
Fallout3 Shader Properties update

Updated BSShaderProperty, BSShaderLightingProperty, BSShaderNoLightingProperty, BSShaderPPLightingProperty and SkyShaderProperty blocks for Fallout3. Added BSShaderFlags2 and their meanings.
Reverted names of Unknowns

Reverted names of two Unknowns in BSShaderPPLightingProperty to "Unknown Float 4" and "Unknown Float 5". Also renamed "Envmap Scale" in BSShaderProperty to "Environment Map Scale" and added its description of funtionality - it is same as "Environment Map Scale" in BSLightingShaderProperty - controls the intesity of the environment map.
Merge pull request #29 from ttl269/feature/Shader-Properties-update

Fallout3 Shader Properties update