Fixes for header warnings in 2.81, as well as a fix for a raycast comment and some new accesors in btConeTwistConstraint

I just completed converting our engine from 2.78 to 2.81 and made several 
changes that I'm hoping will get back into the main trunks. All minor stuff, 
but changes I feel should be made. We're compiling on VS Express 2008 with the 
Warning level 4 set, Win7.

1. We are getting various warnings during compilation of Bullet and our own 
projects, some of them echoing many, many times over. The submitted patch 
(Warnings in Headers.patch) fixes them. Note there were a couple others in 
.cpps I didn't touch. To fix the warning I was getting from btAssert(0) (which 
defines to an if statment in my environment and MSDev doesn't like 0 as a 
comparison statement), I called btFullAssert(0) instead. All cases of this were 
dead end func calls that were supposed to assert if ever called anyways so 
there should be no performance hit from this change. The other cases just dealt 
with parameters that were never used, mostly in interface function definitions.

2. This next one is optional, but if we needed it, others may too. In our game 
I required access to the enabled state and the target of the motor in 
btConeTwistConstraint in order for my algorythm to function correctly. 
Submitted patch (btConeTwistConstraint.h new accessors.patch)

3. I noticed that most of the personal tag "//@BP Mod " comments in the Ray 
Cast code from the old fix to the backface culling ray cast bug were removed 
sometime since 2.78. There is still another in btRayCastCallback.h. I removed 
it and clarified the usage of one of the flags. See (btRaycastCallback.h 
comment fix.patch)

Original issue reported on code.google.com by cont...@vicariousentertainment.com on 2 Nov 2012 at 12:12

Attachments:

[Warnings in Headers.patch](https://storage.googleapis.com/google-code-attachments/bullet/issue-668/comment-0/Warnings in Headers.patch)
[btConeTwistConstraint.h new accessors.patch](https://storage.googleapis.com/google-code-attachments/bullet/issue-668/comment-0/btConeTwistConstraint.h new accessors.patch)
[btRaycastCallback.h comment fix.patch](https://storage.googleapis.com/google-code-attachments/bullet/issue-668/comment-0/btRaycastCallback.h comment fix.patch)

lucas95123 / bullet

Fixes for header warnings in 2.81, as well as a fix for a raycast comment and some new accesors in btConeTwistConstraint #668