Complete library documentation

The main concepts driving this development are:

• Output pins addition to a project without making substantial changes to the standard programming practices referring to output pin values writes and reads.
• Methods and resources are provided to minimize full outputs updating, usually associated with the nature of the GPIO expanders based on SIPO shift registers without preset size limits (changes buffering).
• Pin state reading consistency, even for buffered changes.
• Easy addition of Shift Registers modules by just changing a instantiation parameter.

Note:
I will agree with anybody who catalogs this as a YAUSRL (Yet Another Unneeded Shift Register Library). The thing is I tried to find an adequate library for my project but I failed to find something I felt comfortable working with. As a matter of fact I forked a repository, and after starting to modify it I ended up scrapping the old base concept and started a new structure, using the old code scraps where it was consistent with the new concept, rewriting the rest. As a matter of fact this repository will still be a fork of the original library for it was a source: of code when it fitted my vision, of inspiration when I considered it was outside my vision of the solution concept. The original library repository is at ShiftRegister74HC595.