Version 1 of the reeflective/flags library

Goals

• Support for modern shell completion systems directly derived from the lib's core functioning: best of cobra, best of reflect
• Support local/remote CLI execution and binary builds: client/server commands, while not hampering on the UI part of the CLI, nor its parsing efficacy.
• Enlarging the ability to run command-as-config-files (batch files), which is similar to the usual "config-as-code" suspect. The old flags version would not be able to manage multiple invocations of the same command in the same file/run.
• Refactoring the code so that maintenance is easier, which is supremely important given the core nature of this library (eg. using reflect the right way: to kill the CLI)
• Approaching parity with Cobra's arbitrarily nested structure, without compromising a dime of this flags library.
• Appropriate coverage of these new features.