Merge pull request #5 from Babazka/feature/make_formatColumnName_public

Make formatColumnName public
Support encoding values of pointers, including nil -> NULL
Merge pull request #6 from go-pg/feature/can_write_pointers_and_nulls

Support encoding values of pointers, including nil -> NULL
Don't retry on dbError.
all: add support for sql.Null* types.
encoder: Support full range of pointer data types

After dereferencing a pointer, we pass the value to appendIface (which knows about time.Time etc)
instead of appendValue (which doesn't).
README: listed all supported types
README: links to standard interfaces
Remove debug log.
Use driver.Valuer interface.
Fix setting zero values on NULL

Fixes #7