imGuIZMO.quat v2.1

Changes from v. 2.02

Now the math library has been inserted in a proper repository, so I changed its name from vGizmoMath.h in vgMath.h.
Anyway users no need to change anything in own source code, if they don't want, a vGizmoMath.h "frontend" has been created to load vgMath.h.
(although I recommend to change anyway the #include name in your code)

The vGizmoConfig.h file name also changes in vgConfig.h, but it's used only internally: you don't have to do anything.

Is need only to copy your changes made in vGizmoConfig.h in the new file vgConfig.h.
It contains also 2 new options described in Configure imGuIZMO.quat section to homepage

Also two #defines name are changed to do explicit reference to VGM and not more to VGIZMO:
VGIZMO_USES_LEFT_HAND_AXES ==> VGM_USES_LEFT_HAND_AXES
VGIZMO_USES_TEMPLATE ==> VGM_USES_TEMPLATE
(it's important if you have used external defines to pass to compiler)

In vgMath the following constructors change:

• Vec3(const VEC2_T& v, T s=T(0)) ==> Vec3(const VEC2_T& v, T s)
• Vec4(const VEC3_T& v, T s=T(0)) ==> Vec4(const VEC3_T& v, T s)

(to avoid errors has been removed default assignment: now you explicitly need to add the "scalar".)

• added MAT4_T scale(MAT4_T const& m, VEC3_T const& v) function
• correct a typing error in frustum function name