Add custom word_delimiter fikter

This should allow splitting text by e.g. colon or slash, and searching parts of the word.

Fixes: #31
https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-word-delimiter-tokenfilter.html

config/Elasticorn/docsearch/IndexConfiguration.yaml

@@ -5,10 +5,14 @@ analysis:
     typo3_stemmer:
       type: stemmer
       language: minimal_english
+    typo3_filter:
+       type: word_delimiter
+       preserve_original: true
   analyzer:
     typo3_analyzer:
       filter:
-      - lowercase
-      - asciifolding
-      - typo3_stemmer
-      tokenizer: standard
+        - lowercase
+        - asciifolding
+        - typo3_filter
+        - typo3_stemmer
+      tokenizer: whitespace