Generate source code from templates

This reworks the mktest done in Bash into Ruby/ERB and make it generic, so any kind of stuff can be generated (hence the name).

The command-line tool is not only useful for first-time generation of stuff, but can be also used to update existing files, by creating a <file>.new copy with the new stuff.

This toolkit is intended to be easily extensible by adding new asset packages, as needed.

Changelog

• 1.1 - start with gem stuff
• 1.2 - focus on Ruby 1.9 and use CmdUtil 2.0
• 1.3 - use CmdUtil 3.0
• 1.4 - use CmdUtil 3.1
• 1.5 - use CmdUtil 3.2 and dimensions, usecases rename
• 1.6 - gem: also generate a README.md
• 1.7 - gem: also generate a Gemfile
• 2.0 - focus on Ruby 2.2+ and remove 1.8 compat option
• 2.1 - switch to Ruby 2.4 as baseline
• 2.2 - switch to Ruby 2.6 as baseline
• 2.3 - use CmdUtil 5.1