Feat: keyword param char-bag for trim functions

[kilianmh]

• add keyword parameter char-bag to trim, trim-right, trim-left

• char-bag can be a sequence (e.g. list or string)

• char-bag defaults to *whitespaces*

• update tests for trim functions

• update documentation with examples

Is the parameter name char-bag appropriate? And do you like the documentation (same in docstring and readme)?

[vindarel]

Hi, I like the feature, that's a great addition.

Re naming: is "char-bag" a usual name for this? If it's used in other libraries of other languages, then why not re-use it. If not, let's find a shorter name? (no good idea… simply "chars" ? I'll welcome the opinion of native english speakers, if char-bag is the best self-explanatory, so be it)

I think the examples (in the readme and the docstrings, yeah it's the same, we need to copy-paste one time) could be more straightforward by using strange letters around a common word, like "(trim "xyfooxy" :char-bag "xy"), but that's a nitpick.

[kilianmh]

The change requested should be done.

I chose char-bag because

1. in the CL function string-trim its character-bag
2. in cl-str char is more used in parameters

chars is a straight forward short alternative. In the meantime the name char-set came to my mind. It's same length, however character set is commonly used compared to character bag.

[vindarel]

It's even char-bag for me:

(defun string-trim (char-bag string)
  (generic-string-trim char-bag string t t))

looks good then.

A bit busy, will double check tomorrow.

[vindarel]

Thanks!