Notices, warnings, errors as exceptions in phpunit

- Edit in LinearChainCRFFeatures is to silence the notice
Fixes #27 and #30

It is based on PR #30 from balint42
Add/Improve the tests in Lda

- Added evaluation and assertion of the functional test of Lda
- Added a small test that can be run even with the flag
  --exclude-group Slow
Merge branch 'lda-fixes' into develop

Fixes #27 and #30