[Meera] Introduce 'akhn' rule for mlm2 specification

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>
[Meera] Introduce 'pref' for <Virama,Ra> and new 'pres' lookup table for mlm2 spec
Accomplished via good-old sed script:
sed -i "s/\(Ligature2: \"'pres' Pre Base Substitutions in Malay+AQEA-lam lookup 4 subtable\" \)\(.*\) r4/&\nLigature2: \"'pres' Pre Base Substitutions in Malay+AQEA-lam2 lookup 4 subtable\" r4 \2/g"

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>
[Meera] Introduce 'blwf' rule for <Virama,La> and change 'blws' rule to include 'mlm2' spec also

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>
[Meera] Introduce 'pstf' rule for <Virama,Va> and <Virama,Ya>; and change 'psts' rule to include 'mlm2' spec also

Signed-off-by: Rajeesh K Nambiar <rajeeshknambiar@gmail.com>