imperfect maze method, new tests cases

[OnixTech]

Summary

build imperfect maze.

Fixes #7

Changes

• New method added with an algorithm which delete one wall for each cell which have 3 walls. It filter the edges cells and also that cells which belongs to the pattern.
• Test modificated adding a local pattern.

Testing

• make lint passes locally
• make test passes locally
• Manually tested the behavior described above

Checklist

• PR title follows <TICKET-ID>: short description
• Linked to the correct issue (Fixes #... above)
• No unrelated changes bundled into this diff
• Updated README if this changes user-facing behavior (config keys, controls, etc.)