modify code to suppress or fix warnings in gcc and clang (#41)

* first fix to start branch PR

* explicit conversion from sizet to int

* Array.h and DiagonalMatrix.h

* many sizet to int conversions

* removed some unused variables and added expl overrides

* removed many unused parameters

* more typing

* even more

* last of the easy changes

OndselSolver/ParallelAxesJoint.cpp

@@ -16,7 +16,7 @@ MbD::ParallelAxesJoint::ParallelAxesJoint()
 {
 }
 
-MbD::ParallelAxesJoint::ParallelAxesJoint(const char* str)
+MbD::ParallelAxesJoint::ParallelAxesJoint(const char*)
 {
 }