* Prevent nnn from waiting on open file process

* Add env var flag to not wait for child process when opening file

* Set nowait flag once to skip bit-or every time we open a file

* Add documentation for NNN_NOWAIT

Fix regression from 1e5a0b8c5b.

Check if the number of columns needed to print name exceeds the number of cols.
If it does, split the name str at the max number of columns available for name.
Conversion to wide char ensures the split is done at a valid codepoint.

The current patch adds some optimization as well:

- No more copying to an intermediate (global) string.
- If the name is shortened, escape chars are replaced only till the terminator.

In case of astral symbols like Devanagari matras multiple wide-char codepoints
occupy a single position/column. Positioning the cursor wrt. the actual number
of wide-characters in a wide-char string gets "visually incorrect".  The trick
is to calculate the correct number of columns needed to represent a fixed-size
wide-character string.

Relevant man pages:

1. wcswidth(3)
2. wctomb(3)
3. mblen(3)

Interesting links:

1. https://www.gnu.org/software/libc/manual/html_node/Non_002dreentrant-Character-Conversion.html
2. https://www.gnu.org/software/libc/manual/html_node/Shift-State.html
3. https://10hash.com/c-programming/uchar/
4. https://mathiasbynens.be/notes/javascript-unicode#accounting-for-astral-symbols

Example file names for test:

1. Malgudi Days - मालगुडी डेज - E05. Swami and Friends - स्वामी और उसके दोस्त (Part 5)
2. Eso eso aamar ghare eso ♫ এসো এসো আমার ঘরে এসো ♫ Swagatalakshmi Dasgupta
3. Führer

This reverts commit e8cf0dc663.

Very frequent with Devanagari scripts ('matra's)

F2 is not very portable e.g., doesn't work over putty (default settings).

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