Disable spatial indexes by default
merge nathanlws: Disable spatial indexes by default

Merge pull request #1087 from nathanlws/sql-layer/disable-geo-by-default
https://github.com/FoundationDB/sql-layer/pull/1087
CHAR/VARCHAR do not include prefix, VAR/BINARY has a lenght
All TStrings have charset and collation
merge nathanlws: Tweak i_s.columns {max,octet}_length for (var){char,binary}

Merge pull request #1088 from nathanlws/sql-layer/tweak-length-is-columns
https://github.com/FoundationDB/sql-layer/pull/1088
Enough of the basic data structure to get from CREATE TABLE to AIS (via Protobuf).
Some ALTER support.
Emulated meta-data.
Clean up error handling.
I_S tables.
Add a YAML test for those DDL operations.
Sketch the overall flow.
Clarify multi-column conditions and add a test.
Handle RESTRICT and outline more details of other cases.
Take care of TODO.