html: Add markdown render flag option (#616)

New "flags" option in the [markdown] section to customize
Misaka's Markdown HTML rendering.

By default, no flags are set.

```
[markup]
flags = skip-html, escape, hard-wrap
```

Update CHANGES.rst and add the section to the sample
isso.conf and isso-dev.conf

CHANGES.rst

@@ -4,6 +4,14 @@ Changelog for Isso
 0.12.3 (UNRELEASED)
 -------------------
 
+- New "flags" option in the [markdown] section to customize Misaka's Markdown
+  HTML rendering. By default, no flags are set.
+
+      [markup]
+      flags = skip-html, escape, hard-wrap
+
+  Check docs/configuration/server.rst for more details.
+
 0.12.2 (2019-01-21)
 -------------------
 

docs/docs/configuration/server.rst

@@ -298,12 +298,20 @@ supported, but new languages are relatively easy to add.
 
     [markup]
     options = strikethrough, superscript, autolink
+    flags = skip-html, escape, hard-wrap
     allowed-elements =
     allowed-attributes =
 
 options
-    `Misaka-specific Markdown extensions <http://misaka.61924.nl/#api>`_, all
-    flags starting with `EXT_` can be used there, separated by comma.
+    `Misaka-specific Markdown extensions <https://misaka.61924.nl/#api>`_, all
+    extension flags can be used there, separated by comma, either by their name
+    or as `EXT_`_.
+
+flags
+    `Misaka-specific HTML rendering flags
+    <https://misaka.61924.nl/#html-render-flags>`_, all html rendering flags
+    can be used here, separated by comma, either by their name or as `HTML_`_.
+    Per Misaka's defaults, no flags are set.
 
 allowed-elements
     Additional HTML tags to allow in the generated output, comma-separated. By

isso/tests/test_html.py

@@ -89,6 +89,7 @@ class TestHTML(unittest.TestCase):
         conf = config.new({
             "markup": {
                 "options": "autolink",
+                "flags": "",
                 "allowed-elements": "",
                 "allowed-attributes": ""
             }

isso/utils/html.py

@@ -5,6 +5,11 @@ from __future__ import unicode_literals
 import bleach
 import misaka
 
+try:
+    from backports.configparser import NoOptionError
+except ImportError:
+    from configparser import NoOptionError
+
 
 class Sanitizer(object):
 
@@ -49,9 +54,9 @@ class Sanitizer(object):
 
 
 def Markdown(extensions=("strikethrough", "superscript", "autolink",
-                         "fenced-code")):
+                         "fenced-code"), flags=[]):
 
-    renderer = Unofficial()
+    renderer = Unofficial(flags=flags)
     md = misaka.Markdown(renderer, extensions=extensions)
 
     def inner(text):
@@ -80,7 +85,11 @@ class Markup(object):
 
     def __init__(self, conf):
 
-        parser = Markdown(conf.getlist("options"))
+        try:
+            conf_flags = conf.getlist("flags")
+        except NoOptionError:
+            conf_flags = []
+        parser = Markdown(extensions=conf.getlist("options"), flags=conf_flags)
         sanitizer = Sanitizer(
             conf.getlist("allowed-elements"),
             conf.getlist("allowed-attributes"))

share/isso-dev.conf

@@ -28,6 +28,7 @@ enabled = false
 
 [markup]
 options = strikethrough, autolink, fenced_code, no_intra_emphasis
+flags =
 allowed-elements =
 allowed-attributes =
 

share/isso.conf

@@ -185,6 +185,11 @@ require-email = false
 # there, separated by comma.
 options = strikethrough, autolink, fenced_code, no_intra_emphasis
 
+# Misaka-specific HTML rendering flags, all html rendering flags can be used
+# here, separated by comma, either by their name or as HTML_<flag>.
+# Per Misaka's defaults, no flags are set.
+flags =
+
 # Additional HTML tags to allow in the generated output, comma-separated. By
 # default, only a, blockquote, br, code, del, em, h1, h2, h3, h4, h5, h6, hr,
 # ins, li, ol, p, pre, strong, table, tbody, td, th, thead and ul are allowed.