a2_length_1 and hd_a2 removed from e3

Track change to e3 dev branch
Merge branch 'master' into dev
On dev branch, clone the dev branch of e3
Merge branch 'master' into dev

Conflicts:
	src_ext/Makefile
Merge branch 'master' into dev
Merge branch 'master' into dev
Update doc target - only build for p4_lib.mli
Add some timing examples
+