Fix Compiler Warnings - Zero Hour + Tools - Level 1 warnings

[Mauller]

Related to #482 as a sub task.

Fix all level 1 compiler warnings in Zero Hour + Tools for the Vs22 build.

Only Fix warnings that won't change behaviour or break VC6 compatability.

[Skyaero42]

I've started fixing level 1 warnings. Will try to put a branch/PR up this week

[Skyaero42]

Fixed about 2200 warnings level 1, mostly about implicit conversions that are now explicit.
There are about 25 warnings left, which are beyond my knowledge to judge if fixing them have impact on the game.

The branch can be found here:
https://github.com/roossienb/GeneralsGameCode/tree/fix/warnings-level-1