character order normalization

[eroux]

It would be useful to apply some optional normalization to input strings to that the search gets more accurate:

• 0f7a or 0f7c repeated several times -> 0f7b or 0f7d
• any other vowel repeated several times -> ignore repetition
• vowel + 0f71 -> 0f71 + vowel
• vowel + subscript -> subscript + vowel
• \uOF65\u0FB1 -> \uOF62\u0FB1
• \uOF62\u0FBB -> \uOF65\u0FBB

some these problems are often ignored by etext producers because the layout engines reorder characters without the user knowing (see here), and some fonts combine 0f7a + 0f7a -> 0f7b (which is not really correct)