Added document lines that name the default device drivers.

Also:
- Changed some <htmlurl> tags to <url>.  Now, those links will show their URL addresses (in addition to their names) in info and text pages.
- Added some Atmos-specific function names to its document.
- Fixed some punctuation syntax.
Merge pull request #101 from groessler/something_to_pull

Fix error which slipped in in '-L' command line parameter handling.
Merge pull request #100 from greg-king5/default-drivers

Added document lines that name the default device drivers.
Added doc install target.
Harmonized usage of "KB" and "cc65".
Added command-line argument parsing to the CBM510 and CBM610 targets.
Fixed typo (Ilegal).
Merge pull request #102 from greg-king5/main-args

Added command-line argument parsing to the CBM510 and CBM610 targets.
Merge pull request #103 from greg-king5/typo

Fixed typo (Ilegal).
Streamlined the document author credits.
Merge pull request #105 from greg-king5/author

Streamlined the document author credits.
initial version of a P/M mouse callback
- always use page 6 for P/M mouse cursor
- make cursor character of text mode callback configurable
- change default cursor character of text mode callback from 'plus' to 'diamond'
- set P/M callback as default