Add Unicode tests, fix whitespace, fix docs

Added Unicode tests (and fixed few bugs), changed whitespace script to
proccess markdown files, added new guide to showcase how to work with
Unicode.

util/whitespace.sh

@@ -1,3 +1,3 @@
 #!/bin/sh
-find . \( -iname "*.h" -o -iname "*.c" \) -exec sed -i .bak "s/[ ]*$//" {} \;
+find . \( -iname "*.h" -o -iname "*.c" -o -iname "*.md" \) -exec sed -i .bak "s/[ ]*$//" {} \;
 find . -iname "*.bak" -exec rm {} \;