ENH: single/double value reset method for MinMax

- resets min/max to be identical to the specified value,
  which can be more convenient (and slightly more efficient) than doing
  a full reset followed by add()

- additional MinMax intersects() query, which works like overlaps()
  but with exclusive checks at the ends

- provide MinMax::operator&=() to replace (unused) intersect() method

ENH: single/double value reset method for boundBox

- boundBox::operator&=() to replace (rarely used) intersect() method.
  Deprecate boundBox::intersect() to avoid confusion with various
  intersects() method

COMP: provide triangleFwd.H

applications/test/minMax1/Test-minMax1.C

@@ -44,7 +44,7 @@ using namespace Foam;
 template<class T>
 Ostream& printInfo(const MinMax<T>& range)
 {
-    Info<< range << " valid=" << range.valid() << " span=" << range.span();
+    Info<< range << " good=" << range.good() << " span=" << range.span();
 
     return Info;
 }