STYLE: Conform to ITK coding style guidelines.

[jhlegarreta]

Conform to ITK coding style guidelines:

• Use the this keyword to call to member functions.
• Document the methods when being declared.
• Remove reimplemented methods' documentation.
• Use braces for flow control loops, even if they consist of a single line.
• Use unsigned int types for indexing.
• Make flow control loop variables have a local scope.
• Use pre-increment in recursive control loops.
• Use the appropriate indentation.
• Start comments with capitals.
• Make PrintSelf be the last method of the implementation body.
• Remove uninformative PrintSelf std::cout message.
• Remove itkDebugMacro messages.

[jhlegarreta]

In line with #10 , increase consistency across the toolkit code and improve readability.

[jhlegarreta]

White spaces between brackets and arguments in control flow statement arguments and methods are also recommended by the ITK style guidelines, but this has been subject to changes as per the ITK KW Style if I'm not mistaken.

[thewtex]

CI caught build errors.

[T4mmi]

I'll look into it on Monday

[jhlegarreta]

CI failures were due to oversights I made. 8f3a1a9 should be OK. Also resolved the conflicts and rebased on master.