Prepare printooth for customized colors;

[carlosascastro]

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[carlosascastro]

Pull request with customized colours is waiting for several weeks so my recent commits were aggregated to this.

The work is related to:

• Enhance printer implementations to pass parameters into commands, decide if commands are necessary, implement the switches between Printooth constants and manufacturers protocols;
• Simplify, reduce and improve logic around image processing. Decode is now under default printing images helper since it depends on manufacturers and printer implementation;
• Introduce flush command since some printers need a start print command.

@mazenrashed - can you please revise this and generate a new library release?