ALL: Warnings about inconsistent struct/class declarations

Some types were forward-declared as class but are then declared as
struct. Clang complains about the inconsistency.
ENGINES: Warnings about overloaded virtual methods hiding inherited ones

Clang complains about some overriding methods hiding inherited
overloaded versions. Defining the overloaded methods in the derived
classes as well solves the issue.

Anyway, this is not an ideal design, see: http://bit.ly/12Wje7V
VIDEO: Warnings about '< 0' check on unsigned variable

Wether the variable shouldn't be unsigned or the condition
is useless.
ALL: Change some data-only classes into structs

Compare 3284f44074835c43dc2d21025a51e73042289a58.
On second thought, those are data-only and more like
structs than classes.
Merge pull request #41 from ImperatorPrime/master

KOTOR: More highlighting fixes.
COMMON: add a better workaround for {,v}snprintf

Since Microsoft's functions are not C99 compliant, we use a
workaround by Valentin Milea found here:
http://stackoverflow.com/questions/2915672/snprintf-and-visual-studio-2010
DISTS: Add .gitignore file

It contains some MSVC generated files, as well as an auto-
generated file containing the git version number (for non-
autotools builds, i.e. MSVC)
DISTS: Add autotools stuff to the .gitignore
COMMON: Minor code style fix