Allow XML to use paths relative to DOWNLOADPATH

[smvz]

manga.py -x example.xml -d /path/to/manga

example.xml:

<?xml version="1.0" ?>
<root>
    <MangaSeries>
        <name>Manga 1</name>
        <HostSite>MangaReader</HostSite>
        <downloadPath>manga1</downloadPath>
    </MangaSeries>
    ...
</root>

Running the above command with the example XML file should create and use /path/to/manga/manga1 but currently it will create the manga1 directory alongside manga.py

Alternatively the XML parsing could be extended to include a download path that the manga paths should be relative to, keeping the information in one place, i.e.

<root>
    <downloadPath>/path/to/manga</downloadPath>
    <MangaSeries>
        ...
    ...
</root>

[smvz]

Probably too much of an edge case to be worth changing, but it's worth noting that the merged fix will not allow separate absolute paths in the XML.

i.e. "-d /home/user/dir1" with "/home/user/dir2" will result in "/home/user/dir1/home/user/dir2"

[jklmli]

Yeah, can hack around this by checking to see if the path starts with a delimiter slash - I'll get around to it eventually, but feel free to submit a pull request.

[smvz]

Oh, I did just spot a problem actually. It seems to be caused by self.options.downloadPath being set for a manga, then read again for the next manga.

Say you have "-d /home/user" and three entries in the XML as dir1, dir2 and dir3. It downloads into these locations respectively: /home/user/dir1 /home/user/dir1/dir2 /home/user/dir1/dir2/dir3