Correct doc generation, restore make target results into previous structure.

The following issues are addressed:
(1) This restores doc generation as recursive within the make system.
(2) Restores the resulting make targets (_PROGRAMS, _LTLIBRARIES) placement (i.e. libczmq.la correctly is generated within the src/ directory instead of the root).
(3) Establishes naming the included automake content Makemodule.am from within the appropriate gsl (name from http://karelzak.blogspot.com/2013/02/non-recursive-automake.html).