Additional string formats for configurations/terms?

[jagot]

Do we want to support variations of the string formats used to specify configurations and terms?

E.g., in addition to c"1s2" and T"1S" we could also support

• [x] c"1s²" and T"¹S", which improve readability of the source code (this is how the configurations and terms are printed, anyway), and
• [ ] c"1s( 2)", which is a commonly used format in other codes and would simplify copying-and-pasting.

The first option would require some unicode-regex magic, which might be non-trivial, the second option should be easy. To keep things simple, we should not allow mixing of formats within the same string.

[mortenpi]

:+1: to everything. For the unicode stuff -- a character class [¹²³⁴⁵⁶⁷⁸⁹] + a replace(s, '¹' => '1', ...) call should be sufficient? The superscripts are all single characters in Unicode as far as I can tell.

[jagot]

After 6e8c33d, what remains to implement in this issue is the format c"1s( 2)", which can be done later is we want it.