Clean up deprecated code and fix multiple issues

- Remove deprecated markdown_preview plugin and re-wrote
- Renamed alt_provider.py under words completer
- Fix words completion provider logic and cache handling
- Fix container orientations (VERTICAL -> HORIZONTAL) and add Separators
- Remove unused Gtk imports from search_replace plugin
- Fix event creation parameter order in source_file.py
- Fix typo in source_view.py (_load_pretify_json -> _load_prettify_json)
- Refactor webkit_ui with new load methods and enhanced settings

plugins/code/markdown_preview/markdown/preprocessors.py

@@ -0,0 +1,91 @@
+# Python Markdown
+
+# A Python implementation of John Gruber's Markdown.
+
+# Documentation: https://python-markdown.github.io/
+# GitHub: https://github.com/Python-Markdown/markdown/
+# PyPI: https://pypi.org/project/Markdown/
+
+# Started by Manfred Stienstra (http://www.dwerg.net/).
+# Maintained for a few years by Yuri Takhteyev (http://www.freewisdom.org).
+# Currently maintained by Waylan Limberg (https://github.com/waylan),
+# Dmitry Shachnev (https://github.com/mitya57) and Isaac Muse (https://github.com/facelessuser).
+
+# Copyright 2007-2023 The Python Markdown Project (v. 1.7 and later)
+# Copyright 2004, 2005, 2006 Yuri Takhteyev (v. 0.2-1.6b)
+# Copyright 2004 Manfred Stienstra (the original version)
+
+# License: BSD (see LICENSE.md for details).
+
+"""
+Preprocessors work on source text before it is broken down into its individual parts.
+This is an excellent place to clean up bad characters or to extract portions for later
+processing that the parser may otherwise choke on.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+from . import util
+from .htmlparser import HTMLExtractor
+import re
+
+if TYPE_CHECKING:  # pragma: no cover
+    from markdown import Markdown
+
+
+def build_preprocessors(md: Markdown, **kwargs: Any) -> util.Registry[Preprocessor]:
+    """ Build and return the default set of preprocessors used by Markdown. """
+    preprocessors = util.Registry()
+    preprocessors.register(NormalizeWhitespace(md), 'normalize_whitespace', 30)
+    preprocessors.register(HtmlBlockPreprocessor(md), 'html_block', 20)
+    return preprocessors
+
+
+class Preprocessor(util.Processor):
+    """
+    Preprocessors are run after the text is broken into lines.
+
+    Each preprocessor implements a `run` method that takes a pointer to a
+    list of lines of the document, modifies it as necessary and returns
+    either the same pointer or a pointer to a new list.
+
+    Preprocessors must extend `Preprocessor`.
+
+    """
+    def run(self, lines: list[str]) -> list[str]:
+        """
+        Each subclass of `Preprocessor` should override the `run` method, which
+        takes the document as a list of strings split by newlines and returns
+        the (possibly modified) list of lines.
+
+        """
+        pass  # pragma: no cover
+
+
+class NormalizeWhitespace(Preprocessor):
+    """ Normalize whitespace for consistent parsing. """
+
+    def run(self, lines: list[str]) -> list[str]:
+        source = '\n'.join(lines)
+        source = source.replace(util.STX, "").replace(util.ETX, "")
+        source = source.replace("\r\n", "\n").replace("\r", "\n") + "\n\n"
+        source = source.expandtabs(self.md.tab_length)
+        source = re.sub(r'(?<=\n) +\n', '\n', source)
+        return source.split('\n')
+
+
+class HtmlBlockPreprocessor(Preprocessor):
+    """
+    Remove html blocks from the text and store them for later retrieval.
+
+    The raw HTML is stored in the [`htmlStash`][markdown.util.HtmlStash] of the
+    [`Markdown`][markdown.Markdown] instance.
+    """
+
+    def run(self, lines: list[str]) -> list[str]:
+        source = '\n'.join(lines)
+        parser = HTMLExtractor(self.md)
+        parser.feed(source)
+        parser.close()
+        return ''.join(parser.cleandoc).split('\n')