Improved versions of <C-a>, <C-x>, ~, g~, gu, and gU.

They are all implemented as operators, which allows for composing
with motions/textobjecs, dot-repeating, and better undo.

Also, <C-a> and <C-x> are configurable and can "increment" and
"decrement" not only numbers but words as well.

# Installation

If you don't want word toggling:

```lua
require('vis-toggler')
```

If you do:

```lua
toggler_config = require('vis-toggler.example')
toggler = require('vis-toggler')
toggler.config = toggler_config
```

The table to assign to config need not come from a separate
configuration file, it can be defined in and manipulated from
within visrc.lua as well.

Decimal and hexadecimal numbers are supported. If a number has
leading zeros, its width is preserved.

The letter case of a hex number is either that of any existing
letters, of letters in the last inc-/decremented hex number (if
any), or of the base prefix (0x or 0X).

# Ideas for improvement

Improve <C-a>/<C-x> to support filetype-specific radix notation
and sets of words. Add option to force hexadecimal base even
without explicit prefix.

---

Friendly fork of https://repo.or.cz/vis-toggler.git (I hope, the
upstream will merge it back).

All issues, questions, complaints, or (even better!) patches
should be send via email to
[~mcepl/devel@lists.sr.ht](mailto:~mcepl/devel@lists.sr.ht) email
list (for patches use [git send-email](https://git-send-email.io/)).