group chat: posting a link with CamelCase endpoint text results in a broken link

[urcades]

commit: urbit/urbit@01aaeb7

When a link to a group is formatted like~sampel/dcSpark, the resulting posted link (in this case, to a chat, but presumably elsewhere group links are parsed), is broken, and ends up looking like this:

In this case, it seems like "Spark" has been sent to a new line.

[liam-fitzgerald]

~sampel/dcSpark is an invalid group link. How should we handle these @urcades ?

[jamesacklin]

Let's plan to validate this on the input side, rather than on display or in the parsing.