Allow extension module to hook into the custom tags.
Allow extension module to hook into the custom tags.

Also changed the tagname to be passed as atom rather than list.

huangered/erlydtl,A40in/erlydtl,truqu/erlydtl,aerosol/erlydtl,oxpa/erlydtl,erlydtl/erlydtl,kivra/erlydtl,A40in/erlydtl,project-fifo/erlydtl,kivra/erlydtl,quasiconvex/erlydtl,truqu/erlydtl,erlydtl/erlydtl,erlydtl/erlydtl,project-fifo/erlydtl,wrw/erlydtl,huangered/erlydtl,quasiconvex/erlydtl,chaptastic/erlydtl,campanja-forks/erlydtl,huangered/erlydtl,A40in/erlydtl,quasiconvex/erlydtl,campanja-forks/erlydtl,wrw/erlydtl,chaptastic/erlydtl,aerosol/erlydtl,kivra/erlydtl,truqu/erlydtl,project-fifo/erlydtl,oxpa/erlydtl,campanja-forks/erlydtl,alexr/erlydtl,oxpa/erlydtl,alexr/erlydtl,wrw/erlydtl,chaptastic/erlydtl,aerosol/erlydtl,alexr/erlydtl