Add Parrot_pf_single_sub_by_tag() to packfile API. Additionally, add method first_sub_in_const_table() to PackfileView PMC as a stopgap measure until properly tagged subs are generated.
Enable new API by returning PackfileView instead of Eval from IMCCompiler
Use new packfile API [GH #937]

evalpmc can now be removed.
Remove Eval PMC
ChangeLog and api.yaml entries for #937
Fix failure in c_arg_assert.t (unused assert macros found - src/pmc/imccompiler.pmc: get_packfile_eval_pmc)
I had to remove the code manually. I don't know why `make headerizer` did not remove it.
Fix compile failure introduced by 4d0deaf .

Failure not spotted because you have to already know to run
`perl Configure.pl --maintainer` and
`rm compilers/imcc/imcparser.{c,h}` to regenerate the IMCC grammar;
otherwise `make` will silently not even try to re-compile imcc.{y,l} .

Needs ticket to be opened on this silent issue.
Regenerate imcc grammar.
Merge branch 'new-packfile-api'
This branch removes Eval PMC; IMCCompiler now returns PackfileView instead of Eval.