Reinstate 'half' rules - needed for ICU Layout Engine :-(. This reverts 14bb0fd64467

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>
Reinstate 'pres' rules in combination with 'half' for La, Ya and Va.
Needed for pango <=1.30 and ICU Layout engine :-(.
Test case is മുഖ്യമന്ത്രി

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>
Rachana: Fix dotreph vva (dotreph v1 xx v1)

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>
Add akhn also for vva

ഉവ്വ് was failing without this
Fix dotrephy1yy1 using psts

Added a glyph dotreph+y1 and then used psts rule dotrephy1 y2
to get correct dotrephy1y1 rendering