Fixed mistake where integer division was used for certain format declarations. Added commented-out helpful prints to identify errors.

Fixed mistake with setSlice, ceil function used RealType and division, this would cause integer division at certain format declarations, now uses float only.

The x and b vectors might have different type.

- base class with non-virtual destructor causes undefined behaviour
- missing return statements at the end of non-void functions
- missing const before char* function argument
- reordered initialization of class members
- misleading indentation after for statement
- fixed use of uninitialized variables
- fixed unsequenced modification and access to variables (the C++
  standard does not define the evaluation order of operands, so
  expressions with side-effects such as j++ cause undefined behaviour)

RowLengths was renamed to CompressedRowsLengths.
OpenMP support wads added to matrix-vector multiplication and to scalar
products.
CSR format can use Cusparse for SpMV.

Min. interations feature was fixed in the GMRES method.
Timers for explicit and semi-implicit timestepping were added.

Adding --fast-build optin for the build script to speed-up compilation.