Added support for enabling shader_pipeline shaders using OSG_SHADER_PIPELINE=ON/OFF env var
Added support for setting the shader_pipeline shaders using OSG_SHADER_PIPELINE_FILES=shader.vert:shader.shaderpipeline_frag env var
Added support for setting the maximum number of texture units used by shader_pipeline shaders via OSG_SHADER_PIPELINE_MAX_TEXTURE_UNITS=<num> env var
