Avoid detecting all txt files as application/x-idx-doc
All .txt files were previously detected as application/x-idx-doc MIME type, thus basically breaking printing them.
Whitespaces in MIME files mean OR. We need to use + to make it AND, so that only .txt files that have the 1b44 marker get recognized as application/x-idx-doc.
diff --git a/mime/indexbraille.types b/mime/indexbraille.types index 90de018..dca2c68 100644