Implement diagonal moves and fix some movement-related issues

[Zegeri]

• Fixes Some tiles can be passable in easyrpg, but no in 2k3 #161
• Fixes Direction fix canceled #160
• Closes Implement last missing move commands #155
• Fixes facing-based non-continuous animations

Other notes:

• In vertical/horizontal move cycles, the character waits now a bit each time it reverses its direction.
• The move frequency is now more accurate, but it's still not frame-perfect.
• You can no longer walk through Ib's parents at the start of the game.

[Ghabry]

Compiling fails because of ambigious arguments to the pow-function:

2>..\..\src\game_character.cpp(201): error C2668: 'pow': Mehrdeutiger Aufruf einer überladenen Funktion
2>          D:\Programme\Microsoft Visual Studio 10.0\VC\include\math.h(583): kann 'long double pow(long double,int)' sein
2>          D:\Programme\Microsoft Visual Studio 10.0\VC\include\math.h(535): oder "float pow(float,int)"
2>          D:\Programme\Microsoft Visual Studio 10.0\VC\include\math.h(497): oder "double pow(double,int)"
2>          bei Anpassung der Argumentliste '(int, int)'

[Zegeri]

Could you check if it compiles now well in Visual Studio?

[Ghabry]

will check when I'm home at my laptop

[Zegeri]

I'm rewriting some history to remove my fix of issue #146. Ghabry's 71a6e1d is better.

[Ghabry]

Compiles fine now. Testing...