[ Bug #113803 ] [2.0b1 NT4.0] printing non asci char causes idle to abort

http://sourceforge.net/bugs/?func=detailbug&bug_id=113803&group_id=5470

Add Unicode support and error handling to AsString().  Both AsString()
and Merge() now return NULL and set a proper Python exception
condition when an error happens; Merge() and other callers of
AsString() check for errors from AsString().  Also fixed cleanup in
Merge() and Tkapp_Call() return cleanup code; the fv array was not
necessarily completely initialized, causing calls to ckfree() with
garbage arguments!

(Also reindented some lines that were longer than 80 chars and
reformatted some code that used an alien coding standard.)