Add .gitignore's.

From: Peter Zotov <whitequark@whitequark.org>

git-svn-id: http://caml.inria.fr/svn/ocamldoc/trunk@15483 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Add multind.sty.

This style is missing even from Debian's texlive-latex-extra.

From: Peter Zotov <whitequark@whitequark.org>

git-svn-id: http://caml.inria.fr/svn/ocamldoc/trunk@15484 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Unbreak HTML ocamldoc.

This commit properly runs local ocamldoc via an explicit ocamlrun
invocation, as already done in manual/library/Makefile.

From: Peter Zotov <whitequark@whitequark.org>

git-svn-id: http://caml.inria.fr/svn/ocamldoc/trunk@15485 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Add a manual section on compiler-libs.

From: Peter Zotov <whitequark@whitequark.org>

git-svn-id: http://caml.inria.fr/svn/ocamldoc/trunk@15486 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Update the description of -ppx in ocamlc and ocamlopt chapters.

From: Peter Zotov <whitequark@whitequark.org>

git-svn-id: http://caml.inria.fr/svn/ocamldoc/trunk@15487 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02