v2.4.2: Update XSD for modelModifTimestamp attribute in themes/styler…

…s (for N++ v8.9 update)

v2.4.1: fix About from CollectionInterface to ConfigUpdater

(and other places in code where still said CollectionInterface because of copy/paste from other plugin)

v2.4: Add ability to Update Validators (XSD)

XSD updated to allow optional modelDate attribute (to work with N++ v8.8.9)

Release v2.3: now handles Cloud and -settingsDir setups

also includes internal code-reuse improvements

Prepare for v2.2.1 bugfix release

@alankilborn reported a crash in the chat.  And that lead to a whole slew of bugfixes and UI/UX improvements:
- Error handling for null handle ⇒ though that didn't turn out to be the cause of the crash, it is still best practice (crash was actually caused by a different plugin) [dd57c33]
- Disable logfile Monitoring Mode ⇒ it triggers callbacks for many file-changed events, which can bog down setups that use plugins/scripts that add many callbacks [0349a46]
- Fix progress bar on ConfigUpdater dialog ⇒ makes more-visible progress as each file is processed [588bb32]
- UI/UX: say `Line#123` instead of `#123` in the Validation dialog error list ⇒ Makes it more clear to the user that the number is the line number, not just some internal tracking number [6fc7284]
- Miscellaneous fixes [5d0b4a2]
  - Rename `Done` -> `Close`
  - Rename `Go to Model` -> `Open/Align Model in Other View`
  - Disabled `Validate` button when no file selected
  - Add ephemeral "Please select a file to validate" choice as initially-selected "file" for validation, which will go away once you've made a choice
  - `Open/Align Model` now allows opening the model even when there are no validation errors (or when you haven't even validated yet)
    - it was previously not allowed because the vector it was looking at to find which line number in model-file was 0-length if there were no errors (or no validation done yet); I was able to update the logic to choose line 0 if there was no selection or no validation errors
  - Update `langs.xsd` to check for duplicate `<Keyword name="xyz">` entries
    - NOTE: if you want this feature, you have to delete the old `...\plugins\config\ConfigUpdater\langs.xsd` before launching the ConfigUpdater or ValidateConfigFiles dialogs
- Only allow on Validator dialog ⇒ It could cause problems if more than one dialog were trying to validate at the same time, and there is no compelling reason for allowing multiple instances of that dialog [01d27c7]

Uprev in preparation for v2.2.0 release

Add "Download Latest Model Files" action (#21)

Downloads `stylers.model.xml` and `langs.model.xml` to the appropriate location (starting in temp file, so it can do a MOVE using UAC if it needs permission).

closes #19

bugfix: prevent crash when langs.model has keyword elements but langs…

… target did not

ConfigUpdater v2.0.0: Ready for initial plugin release

ConfigUpdater: v1.99_beta6 = second try (with correct version embedded)