sync2 test: don't rely on runtime.Gosched
Docs: helicopter overview.
Merge branch 'vtocc'
Throttler must log skipped warnings after maxInterval

Currently the throttler warns of skipped messages only at the beginning
of next successful message. This could cause confusion for sudden spikes followed by
long quiet periods. Fix here is to log skipped warning at the end of
maxInterval.
parser: Drop obsolete tokens TABLE_EXPR, etc.
parser: prep work for boolean expressions.
parser: []byte->string for some non-terminals.
parser: boolean_expression -> BoolExpr
parser: drop obsolete tokens
Merge branch 'parser'
Merge branch 'helicopter-overview'
Fix typo in README.
Update README.markdown
Adding exlude_tables parameter to schema commands.

(very useful for MultiSnapshot).
Merge branch 'master' into replication