Cache Lahman db in standard location
Make tbl_sqlite default class more precise
Better printing for src_sqlite
Initial attempt at join
Re-document
Add note about sql in table
Create temporary tables on demand.
Closes #30
Add support for escaping identifiers.
Ensure escape always returns an sql string
Better sql escaping. New build_sql function.
Closes #32
Add oldClass decls so sql works with S4
More sophisticated escaping behaviour
More control when escaping vectors
Use new escaping techniques
Add mutable query class
More escaping fixes/simplifications
Remove load time class checks
Basic framework for compound selects