#110 Add decision/branch coverage

[Jacques Morel]

decision/branch coverage is still very useful to detect
non coverage of implicit blocks
object = null
if (object != null) {
...
}
object.print(); // NPE!

EMMA won't tell you that you have missed a test that
would have encovered that bug.

Implicit blocks exist for loops, switches...

This is something that Clover, Cobertura have.