Remove the comment about binding keys to frequent Tup commands

I rarely find myself using commands like ‘tup monitor’ which a source
code comment describes as a ‘frequently used’ command.  This patch
removes that comment since I do not use them nearly as often as the
comment implies.  The Tup manual also describes most of these as
‘secondary commands’ that users do not often need.
Do not bind a key when creating a Tup-command function

This patch is the first step towards collecting all key-bindings in
one place within the source code.  We create a function for each Tup
command via the tup/make-command-key-binding macro.  In order to put
all key-bindings in one place we must first remove that aspect from
the macro.  This patch changes the macro so that it only defines the
Elisp function for running a Tup command.  The patch also renames the
macro to tup/make-command-function to reflect the change in behavior.
Replace all calls to tup/make-command-key-binding

The previous patch renames the macro and removes the first parameter.
This replaces all uses of the old macro with the new.
Remove comments about the macro tup/make-command-key-binding

The macro no longer exists so we delete the mention of it that appears
in the source comments.
Improve the docstring for tup/run-command-upd

This is the only command that the ‘C-u’ prefix key affects.
Previously that behavior was part of a source comment.  This patch
removes that comment and puts its content into the docstring for the
function in order to improve documentation and its access.
Group all key-bindings together in one place

Previously all key-bindings were in different places and that made it
difficult to look at the code and see exactly which keys it claimed.
This patch groups all of the bindings into one variable definition so
that we can not only easily see the key-bindings, but also easily add
new ones without having to hunt through the code for the right place.
The patch also calls ‘use-local-map’ when activating Tup mode to
ensure that the key-bindings take effect.
Merge branch 'refactor-keys'

* refactor-keys:
  Group all key-bindings together in one place
  Improve the docstring for tup/run-command-upd
  Remove comments about the macro tup/make-command-key-binding
  Replace all calls to tup/make-command-key-binding
  Do not bind a key when creating a Tup-command function
Tweak the documentation strings to satisfy Flycheck

This patch modifies the documentation strings so that they conform to
common Elisp practices and conventions.  This has no effect of
functionality though.
Add some whitespace for readability
Add support for commands ‘refactor’, ‘options’, and ‘todo’

This patch creates functions for running those Tup commands and
provides a key-binding for each.
Document what belongs to the public API

This also explicitly says the project uses Semantic Versioning and
that requires us to declare and document the public API.
Bump the version number to 1.3.0