add support for all basic golang number types

[grische]

This fixes a bug where an int64 was detected for a number larger than the largest int64 number.
The number 9993372000000000000 was detected as int64, despite the fact that it is outside of the limit 9223372036854775807 because 9993372030000000000 % 1 == 0, but well within float64 limits.

If the other data types are unwanted, let me know.

[mholt]

Interesting idea; I think it makes sense to use float when needed, but as for all int types other than int64, I don't think they are commonly used except when there are specific needs to use a certain number of bytes. i.e. I don't see int8 or int16 or int32 very often.

[grische]

@mholt I also think that other types but int might be actually harmful for many use cases. Imagine one is an ID and this ID is of int64 and just incremented. The example json might just contain the first few samples, i.e. turning into an int8 and then causing problems later on.

If you are OK with #141 I will hide this feature behind a flag (--small-ints maybe?) and leave the default to be int.

Note: the size of int is probably already int64, depending on the platform being used.

[grische]

I have prepared a commit for the new flag: a930048

Once we have decided on how to proceed with #144 , I can update this PR.