FSL-style expressions can use unidecode data to smash case and diacritics (#197)

* Read unidecode data, do some plumbing of it

* More unidecode plumbing

* Do the unidecode smashing, but it doesn't seem to be working

* Ah, that's better!

* Add missing header

* And reorder the includes too

* Shortcut when there is no unidecode data to work with

* Update version and changelog

* Avoid repeated unidecode smashing of the same constant string

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 2.44.0
+
+* Add --unidecode-data option to allow case-insensitive filter comparisons of transliterated strings
+
 # 2.43.0
 
 * Change -fraction-as-needed feature dropping to be consistent across tiles and zoom levels, and to follow the same pattern as point dropping by zoom level