Abstract similar code used when loading saves or loading classes

Fixes #1046
Merge pull request #1047 from dorkster/fixes

Abstract similar code used when loading saves or loading classes
don't miss brief button clicks or other inputs

mouse clicks, scroll motions, key presses, and joystick motions that are
activated then de-activated very quickly are now active for at least one
logical frame, so that they are not missed.

Fixes #1048
Check for undefined tiles when validating map tiles

Fixes #1051

We were only checking for tile indexes that were out of the tileset's
bounds. This overlooked tiles that were in bounds, but had no
definition. This commit remedies that.
Merge pull request #1054 from dorkster/fixes

Check for undefined tiles when validating map tiles
Merge pull request #1052 from sudoman/fixes

don't miss brief button clicks or other inputs
Improve error message when a map contains invalid tiles
Add NULL-check for mapping minimap colors

Fixes #1043
Stop attacking when mousing over some menus

Fixes #1053
Merge pull request #1056 from dorkster/fixes

Small fixes
Merge pull request #1057 from dorkster/input

Stop attacking when mousing over some menus
Complete attribute documentaion

This should cover all of Flare's moddable configuration files. Some of
the descriptions might not be perfect, but at least we'll have an
overview of everything we can put in these files.

Of course, the Attribute Documentation wiki page should be regenerated
and updated after this. I added a few new types that should be added to
the top of that page:

* float - a floating point number
* alignment - can be any of: topleft, top, topright, left, center, right, bottomleft, bottom, bottomright
* label - specified as: "hidden" or as: x (integer), y (integer), justify (string), valign (string), style (string); justify can be [left:center:right]; valign can be [top:center:bottom]; style is any font style defined in engine/font_settings.txt

Known issue: The only functionality change I made was to the position
attribute in menus/fps.txt. I changed the old parsing of the corner to
place it in to use the alignment type mentioned above. Yay consistency!
Merge pull request #1061 from dorkster/docs

Complete attribute documentaion
Fix some errors/typos with Attribute documentation
Merge pull request #1062 from dorkster/docs

Fix some errors/typos with Attribute documentation
Remove support for noalpha graphics

Closes #890
Closes #1016
Merge pull request #1063 from dorkster/fixes

Remove support for noalpha graphics