Implemented Array:containsOnlyValue.
Restored implementation of ArrayOperations::memoryCompare on host.

Build of tools can be turned-off. Grid traversers for 1D and 2D has been rewritten using subdomain overlaps.

Implemented a method Array::checkValue which returns true only if there is an element with given value in the array.

double works, not tested for other types.

I don't understand how it could work on the small grids...

Refactoring

See merge request mmg/tnl-dev!3