#565 UTF8 Compliance

[Martin Matuska]

To make database operations UTF8-aware, the following
is needed: "SET CHARSET utf8" after connecting to the
db. The mysqli extension is not yet supported, but it
has its own function for this - mysqli_set_charset.

To make search and indexing UTF8-compliant, functions
like strtolower(), strtoupper() need to be replaced
with mb_strtolower(), mb_strtoupper() to correctly
handle multibyte characters.

With these modifications, UTF8 works very well,
tested with Owl-0.93.