Merge branch 'hotfix/select-time' into develop
Add extra assertion to TestWithTimeSelect()
#87 - add SelectOne() method
add doc comment for DbMap.SelectOne
for columns of type reflect.Ptr, use element type

Fixes all pointers from turning into varchar(255) when creating tables.
Don't log commit/rollback if tx is closed
Add test case for #86.  Fix test cleanup so db.Close() is called.
Restructure README.  Add full example program. Document SelectOne()
Add note about placeholder portability to known issues section.
Merge branch 'release/1.2'