Meta: Follow new nomenclature

[stellaaash]

This PR makes the main start to follow the new nomenclature for the project, as defined below.

Project Nomenclature

• All types (structs, classes, typedefs...) should be in PascalCase
• Variables stick to camel_case
• Files containing only functions are camel_case, while files containing class implementation or interfaces are PascalCase
• Abbreviations (especially in filenames) should be reduced to a minimum, unless it is really idiomatic this way (like i for iterator in a loop)