Fix #66: add += operator to VectorIterator class

It seems that the templated std::sort with clang on OS X 10.9
requires iterators to have a += operator defined. Adding the
operator fixes the broken build.
Fix #66: add -= operator and fix assert

Fix the assert statement per recommendation by @sherm1 and
add -= operator.
Merge pull request #69 from scpeters/issue_66

Fix #66: add += and -= operators to VectorIterator class (needed by OSX 10.9's std library).
Added doxygen to Vec and Mat.
Merge pull request #70 from tkuchida/master

Thanks, Tom! (Added doxygen to Vec and Mat.)
Removed examples that only work in Release mode.
Merge pull request #71 from tkuchida/master

Removed examples that only work in Release mode.
Minor modifications to allow compilation with Visual Studio 2013
(a.k.a. VS 12). Some obscure missing std:: functions were finally
added, and std::max and std::min require <algorithm> to be
included now.
Add adhoc test case showing how to calculate moving muscle point forces correctly (per discussion with Ton van den Bogert and Ajay Seth).
Fix gcc compiler error and warning.
Add paper reference to comments.
Doxygen: fixed line breaks in elementwise Matlab operators.
Fix to doxygen that preserves autobrief.
Merge pull request #76 from tkuchida/doxygenForVec

Doxygen: fixed line breaks in elementwise Matlab operators.
Thanks, Tom!
A step in the direction of better Doxygen documentation for Simbody's vector and matrix classes.
- There is a new doxygen Module (like a "topic") on the vector/matrix stuff. The basic small and large matrix classes now belong to that module (using doxygen's @ingroup command).
- I extracted some text from OpenSim's SimTK matrix library topic and used it to seed the general discussion in the new module, but that needs to be reworked.
- I went through the Vector_ class and documented all the methods (many were undocumented). This needs to be done for all of these classes but you have to start somewhere!
- I added misc. documentation here and there.
Merge pull request #77 from simbody/VecMatDocImprovements

A step towards better Doxygen documentation for Simbody's vector and matrix classes.
Merge remote-tracking branch 'upstream/master'