tpl/tplimpl: Fix compiling Amber templates that import other templates 
tpl/tplimpl: Fix compiling Amber templates that import other templates 

Without this patch, amber would try to load templates from the OS filesystem
instead of the layouts virtual filesystem.
mdhender/hugo,anthonyfok/hugo,anthonyfok/hugo,fedelibre/hugo,gohugoio/hugo,fedelibre/hugo,anthonyfok/hugo,fedelibre/hugo,gohugoio/hugo,mdhender/hugo,mdhender/hugo,mdhender/hugo,fedelibre/hugo,gohugoio/hugo