IsSame() and similar functions

[jftuga]

Could you please update the documentation for IsSame() and its similar functions?

I noticed that this will not always return the correct result:

// d1 and d2 are both of type goment.Goment
d1.IsSameOrBefore(d2)

In order to fix this, I had to use this instead:

d1.IsSameOrBefore(&d1)

In the first example, false could be returned when true should be returned because of this section of code:

goment/goment.go

Line 39 in e67f454

switch v := args[0].(type) {

This switch statement never checks for type Goment -- only for type *Goment. Therefore, false is returned without comparing the dates.

In addition to updating the documentation, you could have the switch statement also check for a Goment type.