Avoid expand_path in require_relative
Avoid expand_path in require_relative

The problem is that at compiler level there’s no reference to the file
on disk or to its path. This makes require_relative a bit less correct
but fixes it for most cases.

Fixes #626
kachick/opal,Mogztter/opal,Flikofbluelight747/opal,suyesh/opal,gausie/opal,gabrielrios/opal,bbatsov/opal,Mogztter/opal,jgaskins/opal,c42engineering/opal,catprintlabs/opal,iliabylich/opal,jgaskins/opal,merongivian/opal,castwide/opal,suyesh/opal,Ajedi32/opal,gabrielrios/opal,Flikofbluelight747/opal,Ajedi32/opal,jannishuebl/opal,castwide/opal,Mogztter/opal,iliabylich/opal,Mogztter/opal,fazibear/opal,domgetter/opal,gabrielrios/opal,kachick/opal,wied03/opal,c42engineering/opal,bbatsov/opal,gausie/opal,opal/opal,fazibear/opal,opal/opal,opal/opal,suyesh/opal,fazibear/opal,domgetter/opal,opal/opal,jgaskins/opal,jannishuebl/opal,gausie/opal,jannishuebl/opal,Flikofbluelight747/opal,merongivian/opal,bbatsov/opal,c42engineering/opal,castwide/opal,catprintlabs/opal,Ajedi32/opal,kachick/opal,wied03/opal,kachick/opal,iliabylich/opal,wied03/opal,merongivian/opal,catprintlabs/opal