slash replacement support (fix yyyyyyyan/bandcamper#10)

[yyyyyyyan]

@UlyssesZh I had to revert the PR, sorry. Can you open it again?

[UlyssesZh]

What is the reason of the reversion? Do I need to change anything?

[yyyyyyyan]

@UlyssesZh Yes, please make the replace on the .move_file() method instead of the download methods. It shoud take only one call to .replace() in line 244:

move_to = self._sanitize_file_path(destination / output.format(**context).replace("/", self.slash_replacement))

[UlyssesZh]

Making that change would be problematic because the template itself may contain slashes that the user want. The unwanted slashes are those in the context. I think my original approach was better.

So what exactly was the reason of the reversion? If you could have not reverted, you can just revert #16.

[Brisppy]

I'm still seeing issues with tracks with slashes. Track 17 of this album titled "VANTAGE // - Get Ready".

You will need #14 merged to test this otherwise the album won't download

~/bandcamper# bandcamper --no-fallback -f flac -v https://stratfordcompilations.bandcamp.com/album/stratford-ct-1-yr-anniversary-compilation
[?] Searching available downloads for URL https://stratfordcompilations.bandcamp.com/album/stratford-ct-1-yr-anniversary-compilation
[+] Free download found! Downloading Ѕtratford Ct. - Stratford Ct. | 1 yr Anniversary Compilation
flac.zip (687.1MiB)  [####################################]  100%
...
[+] New file: /root/bandcamper/Ѕtratford Ct./Stratford Ct. | 1 yr Anniversary Compilation/17 - VANTAGE / - Get Ready.flac
...
[+] New directory: /root/bandcamper/Ѕtratford Ct./Stratford Ct. | 1 yr Anniversary Compilation

Results in track 17 creating a directory:

~/bandcamper# cat "Ѕtratford Ct./Stratford Ct. | 1 yr Anniversary Compilation/17 - VANTAGE "/
cat: 'Ѕtratford Ct./Stratford Ct. | 1 yr Anniversary Compilation/17 - VANTAGE /': Is a directory

~/bandcamper# ls -la "Ѕtratford Ct./Stratford Ct. | 1 yr Anniversary Compilation/17 - VANTAGE "/
total 21880
drwxr-xr-x 2 root root     4096 Dec  8 09:17  .
drwxr-xr-x 3 root root     4096 Dec  8 09:17  ..
-rw-r--r-- 1 root root 22396201 Dec  8 09:17 ' - Get Ready.flac'

[UlyssesZh]

Seems like I missed a place where the slash needs to be replaced. I will probably look into this and submit a new pr during this weekend.

[UlyssesZh]

I'm still seeing issues with tracks with slashes. Track 17 of this album titled "VANTAGE // - Get Ready".

I almost forgot I said I would submit a new pr. Here it is. #20 fixes this problem.