bemhtml: support regular statements
i-bem: use prototypes instead of singleton.

* Share routine functions between render invocations.
* Remove `this._start` predicate, initialize in beginning.
BEM.I18N stub fixes (#317)

* tests

Conflicts:
	blocks-common/i-bem/__i18n/test/test-js-parser.js
More strict rules in i-bem__i18n's deps
(cherry picked from commit 697d0aabe5ec547156a3628b0f5a08aa4de8c709)
Merge pull request #339 from bem/feature-backport-singletone-improvements

Feature backport singletone improvements