implement orthographic rules for FST

Define additional FSTs to implement spelling rules
Gemination: consonant doubling (beg  begging),
Elision: ‘e’ deletion (make  making),
Epenthesis: ‘e’ insertion (fox  foxes), etc.
Y replacement: ‘y’ changes to ‘ie’ before ‘ed’ (trytries)
I spelling: ‘I’ changes to ‘y’ before a vowel (lielying)
Rewrite rule notation: a  b / p _ d
Examples: Rule: a  b/a _ b
aaabaab  aabbabb (Sequential; there are other control strategies: parallel, feedback).
Spelling rules: e  e / x ^ _ s (eg. fox^s  foxes)
Multiple spelling rules might apply for a given word.
Eg: spy^s  spies (yi, ee)
All spelling rules execute in parallel.
Rewrite rules can be compiled into FSTs.