Feature: gluon for concatenating tri-block system

Merge from pull request #15, see details therein.

v0.0.3

Major

• Add trompeloeil mocker for unit test
• Test against AutoMPO element-wisely

Minor

• Run linter against all sources
• Modulize headers to be under hybridleads/

v0.0.2

• New package installed: armadillo for high-level linear algebra.
• Add DMRG test in the hybrid basis and compare with the real-space basis one.