FIXED
- remove global identifier for the black texture
- add black texture 2x2x3 localy on apllication startup
- add special flag to LLViewerFetchedTexture for protect from removing
consolidated most indra-specific constants in llcommon under indra_constants.h
fixed issues with operations on mixed unit types (implicit and explicit)
made LL_INFOS() style macros variadic in order to subsume other logging methods
such as ll_infos
added optional tag output to error recorders