Rebase indent

Rebase a string or an array of indented lines based on the first indentation level.

rebase([' line 1', ' line 2'])
rebase([' line 1', ' line 2'], 4)
rebase(' line 1\n line 2')

``js
rebase(
line 1
line 2
line 3
line 4
);
`

`text
line 1
line 2
line 3
line 4
`

Optionally specify a new base indent (number of spaces). Default is 0.

`js
rebase(
line 1
line 2
, 10);
`

`text
line 1
line 2
``