Update files for v1.6.8.
Bump version to 1.6.9.
disable a couple more /analyze warnings for VS2012
Const correctness. Also pass the argument by reference when possible.
Completely remove RatDVD.

RatDVD was removed from the icon library and file associations in 2307da279e74b216681ef489f38b7e1bd22a04c2.
Remove unused variables.
Replace memset with ZeroMemory.

The ZeroMemory macro makes clear what it does compared to `memset(foo, 0, bar)`.
Get rid of duplicate defines.
Fix the C4701 warnings: Potentially uninitialized local variable "XXX" used.
Use the M_PI and M_SQRT1_2 defines instead of the direct numbers.

Also remove the M_PI fallback define; we always build with `_USE_MATH_DEFINES` defined.

This commit partially reverts dad01b003dc8c5934d8e08fa5dfef9b5536034ef.
Make a couple of functions and pointers constant.
Use ZeroMemory instead of {0} for structs.
Use the struct in the sizeof argument when initializing the struct.
PPageOutput.cpp: use FALSE for BOOL.