Warn about $() but not quotes in 'if $(cmd); ..'
Removed warning for ~ in the middle of strings. Too common.
Fixed UUOC warning for 'cat * | ..'.
Mention second level structure being parsed when error.
Don't warn about f=/dev/null in 'foo $f > $f'
Check for 'echo "\n"'.
Don't warn about quoting when $var is the command name.
Improved help for missing here doc terminator.
Fixed misplaced uuoc for 'cat foo' outside pipe.