Add URL encoding to transfer function to handle whitespaces

[snowphone]

Add URL encoding functionality to the transfer function in README.md so that file names with spaces can be uploaded correctly (e.g. hello world.json).

Also, the code uses the _urlencode function written in Python3. I know not every *nix OS includes Python3 by default but I'm familiar with Python and I don't know how to make it more portable.

This commit includes changes to the following:

• Update the transfer function to use _urlencode for encoding the file names as URL.
• Add the _urlencode function to URL encode the file names.

Since this oneliner is too hard to review, I uploaded formatted code too:
before.txt
after.txt

If this PR is okay, I'll make a PR to tranfer.sh-web too

[aspacca]

hi @snowphone , thanks for the PR

please, see my comment at #546 (comment)

the best solution would be to avoid cat and do not add the filename in the url

cat "$file"|curl --progress-bar --upload-file "-" "https://transfer.sh/$file_name"

vs

curl --progress-bar --upload-file "$file" "https://transfer.sh/"

so no need for urlencode and $file_name

[snowphone]

Wow it's too simple 😂
I changed this PR as you advised.

[aspacca]

if [ -d "$file" ];then file_name="$file_name.zip" ,;(cd "$file"&&zip -r -q - .)|curl --progress-bar --upload-file "-" "https://transfer.sh/"|tee /dev/null;

here $file is a directory, we cd into it and zip recursively sending output to stdout, curl get from stdin the upload file from stdin.
we should change to zip to file and use it for curl

else cat "$file"|curl --progress-bar --upload-file "-" "https://transfer.sh/"|tee /dev/null;fi

same here: it's not enough to remove $file_name, we should remove cat and curl getting the upload file from stdin:

else curl --progress-bar --upload-file "$file" "https://transfer.sh/"|tee /dev/null;fi

transfer(){ 
    if [ $# -eq 0 ];then 
        echo "No arguments specified.\nUsage:\n transfer <file|directory>\n ... | transfer <file_name>">&2;
        return 1;
    fi;
    if tty -s; then 
        file_name=$(basename "$1");
        if [ ! -e "$1" ];then 
            echo "$1: No such file or directory">&2;
            return 1;
        fi;
        if [ -d   "$1" ];then 
            zip_file="$1.zip";
            pushd "$1";
            zip -r -q "$zip_file" . && curl --progress-bar --upload-file "$zip_file" "https://transfer.sh/"|tee /dev/null && rm "$zip_file";
            popd;
        else 
            curl --progress-bar --upload-file "$file" "https://transfer.sh/"|tee /dev/null;
        fi;
    else 
        curl --progress-bar --upload-file "$1" "https://transfer.sh/"|tee /dev/null;
    fi;
}

this should be the proper one: please @snowphone check if it works for you and feel free to push the change :)

thanks