Remove StringDictionary typealias

[volbap]

Proposal:

• Remove typealias StringDictionary = [String: AnyObject]

Reasoning:

• This typealias does not add real convenience but only confusion. Having to type StringDictionary vs. [String: AnyObject] does not make much of a difference, and the former adds the hesitation of "what does it really is?" to any customer using the library, whereas the latter is clearer because it's explicit.

[volbap]

⚠️ Watch out for documentation updates and compatibility issues.

[volbap]

Renaming process checklist:

• Every appearance in code is renamed
• Every according file is renamed
• Project builds successfully
• Tests pass successfully
• There's a deprecation/migration mechanism implemented in code
• README is updated
• CHANGELOG is updated