This allows the input callback function for a buffer to receive multiple
lines at once, instead of the message being split on newline before
being sent to the callback. It adds a new flag, input_multiline, to
control this. This flag defaults to 0 which is the current behavior.
New comparison operators:
- "==*": is matching mask, case sensitive (wildcard "*" is allowed)
- "!!*": is NOT matching mask, case sensitive (wildcard "*" is allowed)
- "==-": is included, case sensitive
- "!!-": is NOT included, case sensitive
- "=-": is included, case insensitive
- "!-": is NOT included, case insensitive