Revert "Deleting some files"

This reverts commit 46bb6d427d9b9f32d15623614b338c46ac14194e.
Revert "Mesh class"

This reverts commit ac5b4025080d7dd7e1a932cbe1752bc557d6ba4d.
Revert "Revert "Mesh class""

This reverts commit 1eb00db6725c6c56dc0dd982174ccb39a2a57644.