Add some command

Improve the online documents. Elastic3rd manual
Add elastic3rd run and elastic3rd post command. Please use -h for detail help.

Strain-Energy Method for any symmetry

Version 2.4.2

• Support all classes of crystal, from cubic to triclinic
• Support CASTEP (windows or linux, under Materials Studio) and VASP
• Support Python2 and Python3
• Support pip installation

Fix a bug

1.1.1

Update README.md

ELASTIC3rd

Calculate the 3rd order elastic constant of crystal(now only support for cubic).