Add new features

[mmhs013]

Add new features in the next version :

• Add intercept in sen's slope results as well as other test results.
• Add more missing value analysis methods.
• Implement numba package to reduce runtime.

[goodbad3]

冒泡，进展如何

[mmhs013]

@goodbad3, Not so good. Working on another project now. Hope that I can start this project soon.