Update various places for what we can do with C++20: - ends_with / starts_with - std::to_array - using instead of typedef - designated initializers - "[[maybe_unused]]" instead of G_GNUC_UNUSED Also remove some unnecessary 'static'
Use the new ascii ctype utils.
Fix some static analysis warnings
clang in CI fails to deduce it, so let's help it a bit.
Implement a crude html-to-text scraper function, to extract plain text from html messages, so we can use it for indexing.
