Add support for sourcing the generated script by not running `initialize` and `run`

[DannyBen]

Discussed in #594

Proposed Solution

Change this:
https://github.com/DannyBen/bashly/blob/2073e837f028f9139e63d44ee485a015a66003ed/lib/bashly/views/command/master_script.gtx#L15-L18

to this:

if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
  initialize
  run "$@"
fi

and add this:

enable_sourcing: development  

to this:

https://github.com/DannyBen/bashly/blob/2073e837f028f9139e63d44ee485a015a66003ed/lib/bashly/libraries/settings/settings.yml#L101-L112

[DannyBen]

Version 1.2.8 is released (changelog) with this change. Thank you all for the feedback and participation.