add the settable sqlx.NameMapper which is a 'func(s string) string' and is run on field names;  it defaults to strings.ToLower.  i'm opting out of the more flexible FieldMapper in pull request 8 / issue #6 because I don't want sqlx *usage* to look too different;  I want all sqlx code to obey the 'db' tag, for instance, and not to require other tags because of customizations
some documentation updates, add docs for NameMapper and make sqlx's package line conform to other packages when running via godoc
add rows.MapScan;  will likely extend this to Row as well
add MapScan and SliceScan to both sqlx.Row and sqlx.Rows, which can be useful when the result set is not known ahead of time, some readme doc changes
fix #17, allow digits in bind query identifiers
Ability to flatten out embedded structs