combine imagehost extractors into a single file

added extractors for
 - hosturimage.com
 - imageontime.org
 - imgupload.yt
 - imgspice.com
 - imgclick.net

All of these would have shared a lot of common code, so i created a base
class for imagehost extractors and put them all in the same file to
avoid clutter.

gallery_dl/extractor/imagehosts.py

@@ -0,0 +1,129 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2016 Mike Fährmann
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+
+"""Extract images from https://img.yt/"""
+
+from .common import Extractor, Message
+from .. import text
+from os.path import splitext
+
+class ImagehostImageExtractor(Extractor):
+    """Base class for single-image extractors from various imagehosts"""
+    subcategory = "image"
+    directory_fmt = ["{category}"]
+    filename_fmt = "{filename}"
+    https = False
+    method = "post"
+    params = "simple"
+
+    def __init__(self, match):
+        Extractor.__init__(self)
+        self.url = ("https://" if self.https else "http://") + match.group(1)
+        self.token = match.group(2)
+        if self.params == "simple":
+            self.params = {
+                "imgContinue": "Continue+to+image+...+",
+            }
+        elif self.params == "complex":
+            self.params = {
+                "op": "view",
+                "id": self.token,
+                "pre": "1",
+                "adb": "1",
+                "next": "Continue+to+image+...+",
+            }
+        else:
+            self.params = {}
+
+    def items(self):
+        page = self.request(self.url, method=self.method, data=self.params).text
+        url, filename = self.get_info(page)
+        data = text.nameext_from_url(filename, {"token": self.token})
+        if self.https and url.startswith("http:"):
+            url = "https:" + url[5:]
+        yield Message.Version, 1
+        yield Message.Directory, data
+        yield Message.Url, url, data
+
+#
+
+class ImgytImageExtractor(ImagehostImageExtractor):
+    """Extractor for single images from img.yt"""
+    category = "imgyt"
+    pattern = [r"(?:https?://)?((?:www\.)?img\.yt/img-([a-z0-9]+)\.html)"]
+    test = [("https://img.yt/img-57a2050547b97.html", {
+        "url": "6801fac1ff8335bd27a1665ad27ad64cace2cd84",
+        "keyword": "7548cc9915f90f5d7ffbafa079085457ae34562c",
+        "content": "54592f2635674c25677c6872db3709d343cdf92f",
+    })]
+    https = True
+
+    def get_info(self, page):
+        url     , pos = text.extract(page, "<img class='centred' src='", "'")
+        filename, pos = text.extract(page, " alt='", "'", pos)
+        return url, filename + splitext(url)[1]
+
+class RapidimgImageExtractor(ImgytImageExtractor):
+    """Extractor for single images from rapidimg.net"""
+    category = "rapidimg"
+    pattern = [r"(?:https?://)?((?:www\.)?rapidimg\.net/img-([a-z0-9]+)\.html)"]
+    test = []
+    https = False
+
+#
+
+class HosturimageImageExtractor(ImagehostImageExtractor):
+    """Extractor for single images from hosturimage.com"""
+    category = "hosturimage"
+    pattern = [r"(?:https?://)?((?:www\.)?hosturimage\.com/img-([a-z0-9]+)\.html)"]
+    https = True
+
+    def get_info(self, page):
+        _  , pos = text.extract(page, '<div id="image_details">', '')
+        url, pos = text.extract(page, "href='", "'", pos)
+        return url, url
+
+class ImageontimeImageExtractor(HosturimageImageExtractor):
+    """Extractor for single images from imageontime.org"""
+    category = "imageontime"
+    pattern = [r"(?:https?://)?((?:www\.)?imageontime\.org/img-([a-z0-9]+)\.html)"]
+    https = False
+
+class ImguploadImageExtractor(HosturimageImageExtractor):
+    """Extractor for single images from imgupload.yt"""
+    category = "imgupload"
+    pattern = [r"(?:https?://)?((?:www\.)?imgupload\.yt/img-([a-z0-9]+)\.html)"]
+    https = True
+
+#
+
+class ImgspiceImageExtractor(ImagehostImageExtractor):
+    """Extractor for single images from imgspice.com"""
+    category = "imgspice"
+    pattern = [r"(?:https?://)?((?:www\.)?imgspice\.com/([^/]+))"]
+    https = True
+    method = "get"
+    params = None
+
+    def get_info(self, page):
+        filename, pos = text.extract(page, '<td nowrap>', '</td>')
+        url     , pos = text.extract(page, '<img src="', '"', pos)
+        return url, filename
+
+#
+
+class ImgclickImageExtractor(ImagehostImageExtractor):
+    """Extractor for single images from imgclick.net"""
+    category = "imgclick"
+    pattern = [r"(?:https?://)?((?:www\.)?imgclick\.net/([^/]+))"]
+    params = "complex"
+
+    def get_info(self, page):
+        url     , pos = text.extract(page, '<img  src="', '"')
+        filename, pos = text.extract(page, 'alt="', '"', pos)
+        return url, filename