gundam: Make ReZEL inherit ModelEntity and use Squirrel initializer.

Some variables are now defined in ReZEL.nut for customization.
Also renamed maxhealth() to getMaxHealth() to override Entity's
definition.
gundam: Make gundam project buildable for 32bit target.

Also added some project dependencies to the solution file for gundam DLL.
gundam: Make StaticBind variables be available in Squirrel initializer.

These variables are not only customizable in initializer script
(ReZEL.nut in this case), but also modify on the fly (while the game is
running).  And we do not need to register a variable twice.

Currently, StaticBind variables are not mandatory in initializer scripts.
gundam: Add key bind of some commands for ReZEL.

The added commands are: reload, get cover, toggle stabilizer and
transform.  Get cover command is not testable for the moment.

Old binding codes are removed from gundam/demo.nut because they should
be called for all ReZEL instances, not only for demo.nut case.
gundam: Add gundam demo to main menu's demo list.

Also fixed a bug in gundam demo script where the main menu does not hide
after selection.  An invocation of initUI() was removed from demo.nut
because the frame process automatically initializes the GUI (the mission
scripts should not call it directly).
Merge branch 'next2' into gd