Magic tool documentation now split into separate files, and referenced
(as a directory) from README, so that users can find docs to any additional
tools (ones not included by default with Tux Paint) that are installed.
Added new --datadir option, to separate path to brushes/stamps/etc. from that of saved files.
Improved docs on where savedir default is.
Made sure --help, man tuxpaint, and OPTIONS docs all covered all command-line options.
Noted SDL_Pango makes locale-specific fonts unnecessary.
Added "--plugindocprefix" option to tp-magic-config, for where docs should go.
Improved plugin API documentation.
Improved layout of man pages a little.
Added --pluginprefix and --dataprefix to tp-magic-config script.
Started a glossary section in API documentation.
Added Table of Contents to API documentation.
Added a manpage for tp-magic-config script.
Created Mirror and Flip Magic tools as plugins (except sound); hooks
added to Magic plugin API to allow starter and starter-undo mirror/flip.
Created Fade and Darken Magic tools as plugins.
Moved magic tool sounds to 'magic'.
Added flip and mirror icons to main Tux Paint UI (used to share magic tools')
Created 'tp-magic-config.sh' to get CFLAGS for compiling magic tool plugins.
Improved magic tool plugin API.
Committed some documentation on magic tool plugin API.
