Maintenance of mechanical submodules (from `models.mechanics`)

[bogumilchilinski]

List of modules to revision and for further refactoring:

• [x] #88

• [ ] #89

• [ ] #90

• [ ] #109

• [ ] #91

• [ ] #92

• [x] #93

• [x] #111

• [ ] #94

• [ ] #98

• [ ] #99

• [ ] #97

• [ ] #100

• [x] #95

• [x] #101

• [x] #102

• [ ] #103

• [ ] #104

• [x] #96

• [ ] #105

• [ ] #106

[bogumilchilinski]

@grzegorzdl , could you collect a list of submodules to assign to owners?