Fix source file encodings where non-ASCII characters are used

For all files that use non-ASCII chars in string or character literals:

 * Convert the file from Windows‑1252 to UTF-8 if needed
 * Convert chars to \u escapes where helpful for clarity
 * Add a BOM if there are still UTF-8 literal characters

Somebody set up us the BOM.
All your chars are belong to us!

Change-Id: Ia7de62bf786c391ecceb1951c685b2b08e812570