Eqsn

Changes:
* Documentation updates (13)
* Added 3 qubit custom controlled gate (14)
* Improved test coverage (14)

This release is a fix for windows multiprocessing.

New features:
* Custom single gates.
* Custom controlled gates.
* Custom two qubit gates.
* Reading out the statevector is now possible, where the state vector of a qubit, and all other qubits which are part of the same state vector, is returned.

Bugfixes:
* Resolved a bug if multiple instances of EQSN have been used

Tests:
* Added a test to check multiple instance errors

New features:
* Combination of Multiporcessing and Multithreading instead of only using processes

Bugfixes:
* Fixed a bug in which probabilities for measurements could be greater than one or smaller than zero, due to numerical errors
* Fixed a bug, in which during the merge of qubits, another command could interfer the instruction and would get lost in the state vector

- Updated to a object oriented style
- Fixed a bug which occured if EQSN was imported but not used and multiprocessing was used in another module