Avoid include subdirs on install cmdline.
First test with LinuxDoc.
Added secured GH_TOKEN env var.
Moved ca65html out of the src directory.

- A HTML generator isn't really the core of a C/asm toolchain.
- A Perl script isn't actually as portable as one might think.
First test of gh-pages push.
Avoid 'cd' in Makefile.
Revert "No linuxdoc here. Documenation is to be maintained as HTML in branch 'gh-pages'."

This reverts commit fcea8951f1dc51cce28cabfc9cfec760a341118a.

Conflicts:
	doc/Makefile
Updated linuxdoc sources from https://github.com/groessler/cc65/tree/gh-pages-sgml.
First test of actual html page push.
Fixed missing target directory.
Added doc goal to top level Makefile.
Test --allow-empty flag.
Maybe rather ignore the git commit status (?)
Some polishing.
Re-introduced toc removal for coding.html and index.html.
Goals from top level Makefile should be known even if empty.
Route standard goals to doc Makefile.

- mostlyclean is empty as there are no intermedite files.
- all is empty as I don't want to have if depend on linuxdoc.
The content in internal.txt is now fully present in the Wiki.
The gh-pages push seems ready for prime time.
Adjusted doc to commit 9aa17b4c537f77fc01d49ab7167b1b3c179c7b9