build: add -annot flag to build flags
Add .gitignore for generated files
Markdown layout fixes, and note that OPAM installs the binary now

Closes #1 and OCamlPro/opam-repository#1100
Alter the `list-annotations` output to include the page number.

Also make the output format more succinct to make it grep/awk-friendly.
The new format is `Page: <comment>\n`. Grep users will need to be
careful to deal with multiline comments, though.

Signed-off-by: Anil Madhavapeddy <anil@recoil.org>
Merge pull request #2 from avsm/annotation-page-numbers

Page numbers in annotations via asvm. Will update the manual for 1.8 release time (it will be found by the standard manual tests).