Add support for | operator

[FredericDesgreniers]

Currently, if multiple inputs lead to the same destination, they all need to be written one by one, for example

'a..'b' => Self
'0'..'9' => Self

Adding the | operator would allow

'a'..'b' | '0'..'9' => Self

[FredericDesgreniers]

Matches can now be concatenated using '|'

Example:

'a'..'z' | _ => Self