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/Solver.cpp

@@ -59,7 +59,7 @@ void Solver::postRun()
 	assert(false);
 }
 
-void Solver::logString(std::string& str)
+void Solver::logString(std::string&)
 {
 	assert(false);
 }