Gns3fy

Enhancement:
- Addressing fixes for Issue 107 ,thanks to Domoninic markusju for your comments.

Disclaimer

- In order to not disrupt current operation , the Python version 3.6 will be the minimal version to execute gns3fy, but the testing phase will run only from version 3.7 onwards.

**Enhancement:**

- Refactored docs for `mkdocs-material` theme
- Improved CircleCI pipeline config to use workflows, parameters and reusable commands
- Changed CI image from `miniconda3` to `circleci`. It has latest `poetry` and `curl` installed, which is needed for testing and publishing coverage.
- Added labels to `create_link` method. [PR-78](https://github.com/davidban77/gns3fy/pull/78)
- Testing is done on a per-python interpreter basis, meaning that `tox` is no longer needed.

**Enhancement:**

- Ability to manipulate SVGs. Added new methods: `create_drawing`, `update_drawing`, `delete_drawing` and `get_drawing`. Ref 66
- Added a `drawing_utils.py` module that have some helper functions to generate SVGs in the Project: `generate_rectangle_svg`, `generate_line_svg` and `generate_ellipse_svg`. Also `parsed_x` and `parsed_y` that helps positions the Nodes and drawings in the canvas.
- Python 3.8 support. Ref 68
- Added `upload_compute_image` to the `Gns3Connector` object. Thanks skeiffer for the contribution. Ref 62

**Fix:**

- Fixes issue closing Project. Ref 71
- Update poetry and fix CI. Ref 64

**Enhancement:**

- Added `drawings` attribute. Used to gather information from `Drawing` endpoint, and for that there is also the `get_drawings` method.
- Added `arrange_nodes_circular` method, which as the name indicates it will arrange the nodes configured on a project in a circular fashion.

**Enhancement:**

- Added `restore_snapshot` to the available snapshot methods of a project

**Fix:**

- Argument specification for project snapshot methods
- Cred argument for user-based authentication with a GNS3 server

- Extended templates functionality with `create_template`, `update_template` and `delete_template`. Which can be used for migrating templates between GNS3 servers

- Added compute endpoint get method from the REST API. [Compute endpoint](http://api.gns3.net/en/2.2/api/v2/controller/compute.html)
- `get_computes`: Retrieves attributes and characteristics of the GNS3 server compute that will run the emulations.
- `get_compute_images`: Lists images configured for a specific emulator on a compute.
- `get_compute_ports`: Lists configured and used console ports and UDP ports on a compute.

- Added projects snapshots attribute and methods. [Snapshots endpoint](http://api.gns3.net/en/2.2/api/v2/controller/snapshot.html)
- `snapshots`: Attribute that stores snapshots names, IDs and created times of a project. Updated by the `get_snapshots` method.
- `get_snapshot`: Retrieves an specific snapshot information.
- `create_snapshot` and `delete_snapshot`: Creates/Delete an specific snapshot