Fix line-wrapping problem

[MetRonnie]

The problem

I had a similar problem to #18 on GNOME Terminal on Red Hat Enterprise Linux 7. If I typed out enough characters to reach the end of the line, the line would wrap back onto the beginning of the same line instead of the next line (until I had typed enough characters to reach the end of the line again, then it would wrap onto the next line). I.e. typing the + char:

user@host:~/foo/bar [master ≡ (3)]$ ++++   # EDGE OF WINDOW

...continuing to type...

++++++ost:~/foo/bar [master ≡ (3)]$ +++++++# EDGE OF WINDOW

The solution

The problem was caused by the symbol definitions, e.g. \xE2\x89\xA1 for the ≡ symbol. As per https://unix.stackexchange.com/a/468983/200655

Bash cannot calculate the length [of wide unicode symbols] correctly, so easiest way could be to escape 2 out of three parts of those wide symbols.

i.e. \[\xE2\x89\]\xA1

[lyze]

Nice find. Thanks!

[MetRonnie]

Ugh, this appears to have caused a really strange problem with VSCode's integrated terminal when I try to activate a conda environment in it.

Integrated terminal:

user@host:~/foo [master ≡]$ conda activate myenv
# >>>>>>>>>>>>>>>>>>>>>> ERROR REPORT <<<<<<<<<<<<<<<<<<<<<<
Traceback (most recent call last):
      File "~/miniconda3/lib/python3.7/site-packages/conda/cli/main.py", line 138, in main
        return activator_main()
      File "~/miniconda3/lib/python3.7/site-packages/conda/activate.py", line 1093, in main
        print(activator.execute(), end='')
    UnicodeEncodeError: 'utf-8' codec can't encode characters in position 95-96: surrogates not allowed
...
user@host:~/foo [master ≡]$ cd ..
user@host:~ $ conda activate myenv
(myenv) user@host:~ $ # So that worked
(myenv) user@host:~ $ which conda
~/miniconda3/bin/conda

Normal/GNOME terminal:

user@host:~/foo [master ≡]$ conda activate myenv
(myenv) user@host:~/foo [master ≡]$ # Works!
(myenv) user@host:~/foo [master ≡]$ which conda
~/miniconda3/condabin/conda

[MetRonnie]

Sorry for dumping all this here, but I can't think of a better place for it.

More debugging in the VSCode integrated terminal (fresh terminal):

$ which conda
~/miniconda3/condabin/conda
$ conda activate myenv
# Error report blah blah
$ which conda
~/miniconda3/bin/conda

So that doesn't appear to be the problem. Actually, the line-wrapping issue doesn't exist in the VSCode terminal using posh-git.sh as it was prior to this PR.

The setting Terminal > Integrated: Detect Locale has in its description:

VS Code's terminal only supports UTF-8 encoded data coming from the shell.

so I suspect that's the crux of the issue