Add ResolveFilename to ITemplateResolver

Add ability to debug templates that are not stored on disk.
The ITemplateResolver.ResolveFilename must provide the on disk
filename. In addition the CompilerErrorCollection will contain
useful filenames in case of compile errors.
Add ResolveFilename to ITemplateResolver

Add ability to debug templates that are not stored on disk during
execution.
The ITemplateResolver.ResolveFilename must provide the on disk
filename. In addition the CompilerErrorCollection will contain
useful filenames in case of compile errors.