Add support for more languages in Sphinx #245.

Added charset tables for Cherokee, Lao, Mon, Sinhala, Tamil, Telugu
and Tibetan. The Tibetan is temporary because I’m not sure about
including marks and other various symbols.
Fixed random sentence ids.

Reverted part of 1158508bb9fe535a2045aa5230cc62370a81cc56 since
it breaks the random sentence feature.
Tibetan and Lao don’t use word boundaries.

According to Wikipedia [1], these languages don’t use word boundaries.
As documented by Sphinx [2], one must set ngrams_len to 1 for such
languages. I tested searching in Lao with the word for cat “ແມວ”.
For Tibetan, I need to make sure the charset_table is good.

[1] https://en.wikipedia.org/wiki/Category:Writing_systems_without_word_boundaries
[2] http://sphinxsearch.com/docs/current.html#conf-ngram-len