Switch to a hash syntax start and end card delimiter

[alanxoc3]

The inside of the card wouldn't change besides not backslashing gt and lt signs anymore. Here is a complex example of the syntax:

This:

#:hello#:me::#:h\#:ey|yo:#:y{::\# e|:s}:#
or shorter,
#:hello#:me\:#:y{\# e|s}:#

Would generate:

#: hello
#: me\:
#: y{}s | \# e
#: y\# e{} | s
:#