Make it possible to create erlydtl beam files with full path in the name

if DTL_FULL_PATH=true
  /templates/a/b/c.dtl -> a_b_c_dtl.beam
otherwise (as it was before)
 -> c_dtl.beam


full path in .beam file makes it possible to create templates with the same names in different directories. Can be useful for DSLs or just for uniformity of names.