Fix various errors in Modi script

[akprasad]

Mainly errors in hrasva/dirgha vowels.

See: https://unicode.org/charts/PDF/U11600.pdf

This scheme is defined correctly in aksharamukha-py but is not live on the Aksharamukha UI.

[akprasad]

Here are the changes I made to vidyut-lipi, if helpful:

        overrides = {
            "\u0907": "\U00011602",  # letter i
            "\u0908": "\U00011603",  # letter ii
            "\u0909": "\U00011604",  # letter u
            "\u090a": "\U00011605",  # letter uu
            "\u090b": "\U00011606",  # letter vocalic r
            "\u090c": "\U00011608",  # letter vocalic l
            "\u093f": "\U00011631",  # sign i
            "\u0940": "\U00011632",  # sign ii
            "\u0941": "\U00011633",  # sign u
            "\u0942": "\U00011634",  # sign uu
            "\u0943": "\U00011635",  # sign vocalic r
            "\u0944": "\U00011636",  # sign vocalic rr
            "\u0960": "\U00011607",  # letter vocalic rr
            "\u0961": "\U00011609",  # letter vocalic ll
            "\u0962": "\U00011637",  # sign vocalic l
            "\u0963": "\U00011638",  # sign vocalic ll

            "\u0964": "\U00011641",  # danda
            "\u0965": "\U00011642",  # double danda
        }