feat: Add support for overriding commands

[TekWizely]

• Allows overriding commands as long as they are defined in different Runfiles
  • Still can't define a command multiple times in same Runfile
• Command's list position based on first occurrence
• Command's display name based on first occurrence

bug: Display Runfile in post-parsing error reporting
chore: Capture Runfile in ast.Cmd and runfile.RunCmd
chore: Add builtin flag to config.Command

---

cc: @MadBomber Care to give this a test drive / once-over ?

[MadBomber]

The way I'm reading this is that the command name as first defined w/r/t case will be in the list. I ASSUME that goes for the help text as well e.g. the help text of the first definition is what is displayed.

I'm hoping that I'm wrong. Seems to me that when the duplicate is encountered, its name case and its help text should be what is displayed in the list.

[TekWizely]

(I can't find this comment in the review section?)
Hey there! So, as coded the name case and list placement is taken from the first occurrence of the command, but everything else about the command, help text, doc-block args and variables, etc are all taken from the duplicate command.

[MadBomber]

This would be a good place to redefine command1 with different help text to show how it redefines the command1 that was included.... or something like that.

[TekWizely]

Hey! Did you see the output of the list commands example just below this? re:

 command1    defined in Runfile-include
 command2    defined in Runfile

The ## defined in * is the help text in the example

ie. the include file does redefine command1 with different help text ...

[TekWizely]

Hey @MadBomber thanks for helping review this - I left a couple replies for you.

[TekWizely]

It occurs to me that it might be meaningful to allow copying the original command's help text when a duplicate command doesn't provide any of its own.

The original command is expected to be the most canonical, with duplicate commands likely being a bit more slap-dash, ie:

Runfile

##
# My fancy command.
# This command is expected to a very useful thing, let me tell you more ....
#
command:
    ...

Then duplicates don't have to bother with duplicating the actual (and likely useful) help text.
Runfile-include

command:
  ...

The duplicate could get the default help text for free simply by not defining their own help text.

I'll grind on this some more, but I think this will be a useful addition ...

[TekWizely]

It occurs to me that it might be meaningful to allow copying the original command's help text when a duplicate command doesn't provide any of its own.

@MadBomber , so I did end up adding the feature to copy the first command's documentation (title + description) if an overriding command does not define their own.

[MadBomber]

I believe you have accomplished your design goal.

[TekWizely]

I believe you have accomplished your design goal.

@MadBomber Thanks for the assist, merging now !