Start implementing the rules from HJK EKS

where
  HKJ = Heiki-Jaan Kaalep
  EKS = Eesti käänamissüsteemi seaduspärasused
Add IVb (but some cases not handled yet)
Fix IVb, add Va, Vb
Add VI and VII (but grade changes not implemented)
Preliminary (buggy) grade changes
Add preliminary smart paradigm
Merge pull request #1 from GF-Estonian/hjk

Merging an initial implementation of HJK EKS