additional postgres types + attribute name converter

The postgres store now supports all geometric data types.

There are also two new store options externalAttributeName and internalAttributeName for all stores.
Both options are optional and expect a method in the form of function(fieldName: string): string

With externalAttributeName you can convert your internal database field names into another format. e.g. from snake_case to camelCase. The conversion is up to you!
internalAttributeName should handle the opposite way.