Fix regression in shebang detection
Fix regression in shebang detection

00d453a (Don't fail when there is binary input, 2015-09-30)
introduced a regression with shebang detection. Since the data
is read as bytes rather than UTF-8 the comparison does not match
any more. This patch fixes that problem. Additionally the data
has to be converted to UTF-8; otherwise guess_lexer() fails.

rumpelsepp/c.py,rumpelsepp/c.py