Update date bugs

[muazhari]

What I did:

• Remove unused library.
• Change regression_forecast method from using date class operator overloading to the basic method.
• Add data options to the regression_forecast method.

What I found:

• I think this code below in the regression_forecast method should be fixed. Because when the sample is defined and not the same as real data, it should not see another data except the sample right? and should not calculate from that too.

  var mean = this.mean(options.data);

[muazhari]

hello, can my pull request get merged? because there has an unremoved unused third party library that will make the usage of this library dwindled.