building tests in cmake and more general test harness

testrb target will be built from src/test/RevBayesCoreTestMain.cpp
and that executable's return code will be the number of failing tests
Changes to reading of standard data type from NCL

The StandardState labels member will probably lack
the '-' and '?' characters. So setting the states
to these codes should probably be done with special
setGapState and setMissing methods.
The StandardState's stateIndex is problematic because
not all states have an index. in particular the gap
state (treated here as as all 0 bits as other datatypes
treat this "state") and the missing state cannot be
mapped to one index. So this data member has been
removed. The previous accessor now calculates the index
on the fly - and fails with an assertion error if the
state is 0 or has more than one bit "on".
bug fix: default value of bool member

At least on ubuntu with gcc 4.9.1 this
data member is not always initialized leading to
unpredictable behavior wrt whether the likelihood
is calculated.
more stringent tests by comparing to values from PAUP
more testing on tutorials
Cleaning up.
Merge branch 'language-edit' of https://github.com/revbayes/revbayes into language-edit
Merge branch 'standard-state-test' of https://github.com/revbayes/revbayes into language-edit

Conflicts:
	src/core/dag/DagNode.cpp
Cleaning up tutorial output.