more example progs cleanup.
If python not installed, don't link python!
Merge pull request #182 from linas/link-fix

If python not installed, don't link python!
build-knobs: defer calculation
knob building: optimize perm creation.

Build a complete array of permitted pairs, as before.  However,
don't bother creating the combo tree until we actually select a pair.
This should save both a lot of RAM and CPU cycles.
Merge pull request #183 from linas/moses

Moses knob building optimization
Minor comment fix
Add preliminary comment
Fix {vector,list,set} comprehension so that it can use lambda
Merge pull request #184 from ngeiswei/list_comprehension

Fix {vector,list,set} comprehension so that it can use lambda
Implement filter in comprehension
Improve comment in comprehension.h
Merge branch 'master' into target_per_deme
Add some missing methods in CTable to compress further after feature selection
implement cscore_base::ignore_idxs and inherited classes

This method allows to possibly optimize evaluation if many features
are ignored (filtered out, during feature selection within moses).

It also allows to know the best possible score at the deme level
rather than globally.

For the moment on precision_bscore implements one, the other scorer
use the default empty one (i.e. doing nothing).