Tokenization will respect the order in which tokens are defined

From this commit, vst_tokenize() will arrange the tokens in the same
order as specified in the scheme file. This is required to improve
learning. With this change, learn should always learn most used tokens
before it gives up.

This commit also removes VST files. It needs to be compiled before using
Reducing noise from tokens while learning

When combination of tokens exceeds maximum number of patterns that can
be learned, we do a noise reduction on the tokens array. The algorithm
basically finds the largest array and pops elements from the last till
it gets the required number of tokens. Since tokens are ordered
according to the importance, removing tokens from last will only remove
unimportant tokens.

This commit also reduces allowed number of patterns from 100 to 32
Tokenization improvements to improve learn quality. #2 & #3

(1) Ensure ordering of tokens is preserved as specified in the scheme
file.

(2) Introduces an optional 'priority' filed which can be used to change
the token ordering. High priority tokens comes left in the tokenization.

(3) Better priority based noice reduction while learning. In the case of
too much patterns to learn, noice reduction will kick in. In the first
phase, it will remove all low priority tokens. Second phase will remove
tokens from the largest array or the array which has comparatively low
priority tokens.

(4) Rewritten Malayalam scheme file to reflect new changes. This has
considerably reduced the number of tokens. It was 22,000+ tokens before
and 5000+ now!
Introducing accept conditions for tokens - #2

Accept conditions can be specified while declaring tokens. It affects
the way noice reduction works and producing better results with noice
reduction.

First stage of noice reduction will remove all unacceptable tokens.
Accept conditions are specified based on the location in which token
appears in the string.

This commit also removes libvarnam's ability to generate consonant-vowel
combinations. We offload that work to varnamc compiler. This is more
generic and more user controlled so that lot of unnecessary weird tokens
won't be generated
Fixed #11