#8 rars crashes on error function

[Eugen Treise]

When the void error( const char * error_text); function
(defined in g_global.h) is executed, rars crashes in
Windows.
TBitmap class uses error, and if a bitmap file was not
found, it crashes.

Replacing with the function void exitOnError(const char
*format, ...) from misc.h the problem seems to be
resolved, a messagebox with the error text appears and
rars closes normaly.

So error function must be reviewed or replaced by the
exitOnError function.