Add support for more types

[kniren]

In addition to the four main types (Strings, Int, Float, Bool), the next candidates for new types are:

• Date (time.Time)
• Decimal (big.Int/Rational for currency analyses)
• Complex (complex64/complex128)

The pros and cons of these additions have to be taken into account, since every new type increases the complexity of the library significantly.

[guduxingzou]

看到您的这个计划，无以言表的喜悦，太开心了,very happy。ths 感恩！

forgive me use chinese.

[shixzie]

Just created a PR adding partial support for time.Time see here

[crosslogic]

Yes please, I give my vote to time.Time. It's really neccesary.

[guduxingzou]

hello 大神 期待 Date（time.Time） type

[zenhorace]

any idea when int64 may be supported? Is it currently being worked on?