Add version upgrade plug-in for 4.9

Needed to happen at some point...

Contributes to issue CURA-7787.

plugins/VersionUpgrade/VersionUpgrade48to49/VersionUpgrade48to49.py

@@ -0,0 +1,91 @@
+# Copyright (c) 2020 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
+
+import configparser
+from typing import Tuple, List
+import io
+
+from UM.VersionUpgrade import VersionUpgrade
+
+
+class VersionUpgrade48to49(VersionUpgrade):
+    def upgradePreferences(self, serialized: str, filename: str) -> Tuple[List[str], List[str]]:
+        """
+        Upgrades preferences to have the new version number.
+        :param serialized: The original contents of the preferences file.
+        :param filename: The file name of the preferences file.
+        :return: A list of new file names, and a list of the new contents for
+        those files.
+        """
+        parser = configparser.ConfigParser(interpolation = None)
+        parser.read_string(serialized)
+
+        # Update version number.
+        parser["metadata"]["setting_version"] = "17"
+
+        result = io.StringIO()
+        parser.write(result)
+        return [filename], [result.getvalue()]
+
+    def upgradeInstanceContainer(self, serialized: str, filename: str) -> Tuple[List[str], List[str]]:
+        """
+        Upgrades instance containers to have the new version number.
+        :param serialized: The original contents of the instance container.
+        :param filename: The original file name of the instance container.
+        :return: A list of new file names, and a list of the new contents for
+        those files.
+        """
+        parser = configparser.ConfigParser(interpolation = None, comment_prefixes = ())
+        parser.read_string(serialized)
+
+        # Update version number.
+        parser["metadata"]["setting_version"] = "17"
+
+        result = io.StringIO()
+        parser.write(result)
+        return [filename], [result.getvalue()]
+
+    def upgradeStack(self, serialized: str, filename: str) -> Tuple[List[str], List[str]]:
+        """
+        Upgrades stacks to have the new version number.
+
+        This updates the post-processing scripts with new parameters.
+        :param serialized: The original contents of the stack.
+        :param filename: The original file name of the stack.
+        :return: A list of new file names, and a list of the new contents for
+        those files.
+        """
+        parser = configparser.ConfigParser(interpolation = None)
+        parser.read_string(serialized)
+
+        # Update version number.
+        if "metadata" not in parser:
+            parser["metadata"] = {}
+        parser["metadata"]["setting_version"] = "17"
+
+        # Update Display Progress on LCD script parameters if present.
+        if "post_processing_scripts" in parser["metadata"]:
+            new_scripts_entries = []
+            for script_str in parser["metadata"]["post_processing_scripts"].split("\n"):
+                if not script_str:
+                    continue
+                script_str = script_str.replace(r"\\\n", "\n").replace(r"\\\\", "\\\\")  # Unescape escape sequences.
+                script_parser = configparser.ConfigParser(interpolation=None)
+                script_parser.optionxform = str  # type: ignore  # Don't transform the setting keys as they are case-sensitive.
+                script_parser.read_string(script_str)
+
+                # Update Display Progress on LCD parameters.
+                script_id = script_parser.sections()[0]
+                if script_id == "DisplayProgressOnLCD":
+                    script_parser[script_id]["time_remaining"] = "m117" if script_parser[script_id]["time_remaining"] == "True" else "none"
+
+                script_io = io.StringIO()
+                script_parser.write(script_io)
+                script_str = script_io.getvalue()
+                script_str = script_str.replace("\\\\", r"\\\\").replace("\n", r"\\\n")  # Escape newlines because configparser sees those as section delimiters.
+                new_scripts_entries.append(script_str)
+            parser["metadata"]["post_processing_scripts"] = "\n".join(new_scripts_entries)
+
+        result = io.StringIO()
+        parser.write(result)
+        return [filename], [result.getvalue()]