optimized tokenizer (separate indexing/querying and blended/non-blended codepaths, ascii7 and utf8 encoding short-circuits, and other microoptimzations), 1.1x-1.6x sbcs and 1.3x-2.6x utf8 tokenizer speedup, 1.1x-1.25x indexing and snippets speedup

git-svn-id: http://sphinxsearch.googlecode.com/svn/trunk@3648 8b96e2b9-35c5-2c16-bc47-5122d61876d4