Support Int64, Int32, etc for predicates

[bridger]

I have a column declared to be of type Int64. However, this line doesn't compile:

let deviceID: Int64 = 3
let deviceUpdate = Update(devices, set: [(devices.name, name)]).where(devices.deviceId == deviceID)

This is because Predicate.swift and Subqueries_GlobalFunctionsAndExtensions.swift expect a generic-sized Int rather than Int64.

As a continuation of #78 I think it makes sense to get rid of the .int(Int) case and add .int64(Int64), etc types.

[xeokeri]

Would suggest support for UInt as well, along with these. As it seems to only support comparisons to signed integers only.