Add developer version number handling to `fpm.toml`

[nedtaylor]

Motivation

Allow letters and special characters in the project version number in fpm.toml for improved package development version tracking.

Currently, fpm.toml only allows version numbers in the format X, X.Y, and X.Y.Z, where X, Y, and Z are numbers. When working on a development/feature implementation version of a code, it is useful to suffix the version number with something like 1.0.0-dev0 to help track and test.

Specification

Suggested type of allowed version format:

version = "1.0.0-dev0"

If it needs to be restrictive in what it expects to find, then accepting only optional suffixes such as the following seems like they'd be best:

X.Y.Z-dev[0-9]*
X.Y.Z-pre[0-9]*
X.Y.Z-rc[0-9]*

Prior Art

This is often accepted by package managers such as pip.

Additional Information

Formatting of version numbers like this:

https://github.com/callowayproject/bump-my-version

Existing output when trying this:

<ERROR> *cmd_run* Package error: Invalid character in version number
  | 1.0.0-dev0
  |-----^^

or:

<ERROR> *cmd_run* Package error: Too many subversions found
  | 1.0.0.1
  |-------^
STOP 1