Bump version to 1.2.0 and prepare 1.3.0 development cycle.

Don't assume that there is a window displaying the buffer when
`bookmark-jump` is called. Instead of `bookmark-after-jump-hook` use
`window-buffer-change-functions` so that the buffer is actually
displayed when the code assuming a window is run.

If `window-buffer-change-functions` isn't bound fallback to
`bookmark-after-jump-hook`. The window argument for the inserted hook
is optional to accommodate both cases.

Use `window-buffer-change-functions` only if buffer has not window.
Save the same bookmark if it wasn't restored

Closes: #188
Author: @aikrahguzar

Notes from the original PR:

The dependencies for android in autobuild can not be installed in
pdf-tools-install, they have to be installed manually in Termux. But
the dependencies are checked when running autobuild.

pdf-tools-install successfully installs epdfinfo in Android Emacs. One
can then view pdf files.

The shebang in autobuild does not work in Termux, I therefore had to
create a separate script "autobuild.android" that in turn executes
autobuild. The problem with the shebang is that "env" in Termux is not
located at "/usr/bin/env".

pdf-tools/Makefile does currently not work in Android Emacs, but it is
not needed for running pdf-tools-install. Fixing this will have to be
done in a separate pull request, if deemed necessary. Reason: There is
yet no consensus for how to implement a command line emacs, to be run
in batch mode, in Android Emacs.

I have successfully run "make test" in Ubuntu, in the repo feature
branch. Running "make server-test" in the master branch fails, so I
have not tested this in the feature branch.

Closes: #230
Author: @johanwiden

Add gamma correction options for better contrast control in midnight mode:
- pdf-view-midnight-gamma: nonlinearly scale lightness (default 1.0)
- pdf-view-midnight-gamma-before-invert: control gamma application order

Bug fixes:
- Fix RGB normalization (255 not 256) - was causing incorrect background color
- Add missing black→foreground fast path (comment existed but code was missing)

Closes: #329
Author: @vizziv

Add support for horizontal scrolling using mouse wheel by setting
mwheel-scroll-left/right-function to image-mode's scroll functions.

Includes boundp checks for compatibility with older Emacs versions.

Closes: #234
Author: @aikrahguzar

Fix "epdfinfo: No such annotation: annot-X-Y" error caused by
annotations getting out-of-sync between buffer and epdfinfo cache.

Add pdf-annot--ensure-fresh function that fetches fresh annotation data
from the server before modifying, deleting, or interacting with annotations.

Fixes: #246
Closes: #260
Author: @bramadams