Add OSLHOME option to SConstruct
Add OSLHOME option to SConstruct

This is used to ensure OSL is available when building the documentation. Otherwise tutorials which requires OSL may generate incorrect images.

Also fixed incorrect wording on APPLESEED_ROOT option.

johnhaddon/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,hradec/gaffer,lucienfostier/gaffer,ivanimanishi/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,hradec/gaffer,hradec/gaffer,andrewkaufman/gaffer,chippey/gaffer,andrewkaufman/gaffer,lucienfostier/gaffer,hradec/gaffer,ivanimanishi/gaffer,boberfly/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,chippey/gaffer,ImageEngine/gaffer,appleseedhq/gaffer,chippey/gaffer,ImageEngine/gaffer,boberfly/gaffer,ImageEngine/gaffer,hradec/gaffer,johnhaddon/gaffer,boberfly/gaffer,ivanimanishi/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,boberfly/gaffer,chippey/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,ImageEngine/gaffer