-Fix (#164): structure fails to deploy units when partially surrounded.
-Fix (#165): don't reset countdown if saboteur could not be created (patch by wangds)
-Codechange: name a few variables
-Codechange: the word is "immediately"
"
-Fix (#137): an AI can always build anything he wants, the cheater
-Codechange: don't declare a var twice in the same file
-Codechange: Orientation functions are implemented in tile.[ch]
-Codechange: const correctness; tnx GCC!
-Add: next to Error, introduce Warning, for those things that we don't need to nag the user about, but do want to log.
-Fix: a deviated unit could fool the AI in not coming out of their hybernation

It is very unlikely someone ever noticed this, as to become deviated,
you already have the AI out of hybernation.
-Codechange: one more const correctness; tnx mingw
-Fix (#109): a unit delivered to the world by carry-all was not seen as enemy by the AI
-Fix (#118): allow cancel of upgrade if structure gets damaged (patch by dsw)
-Fix (#166): do not select unit's original location after issuing target.
-Codechange: use enum Screen when refering to a screen block
-Codechange: make gui.h slightly more readable (or at least, more sensible)
-Codechange: SCREEN_0 === SCREEN_1, etc, so name them identical.
-Codechange: forgot one SCREEN_
-Codechange: missed a few SCREEN conversions
-Codechange: declare some functions and variables static