new repl prompt can not handle multiline paste

[jurgenvinju]

Describe the bug

• the previous repl could accept a pasted list of imports and execute them. that came in very handy once in a while.
• with an empty line the old repl would print "cancelled". that wasn't very handy because code in a source module often has empty lines.
• the new repl recognizes "pasted" input (it print it already visually differently than typed in commands

So the proposal is to extend the code that currently handles pasted input and execute the entire pasted text as a list of commands, instead of a single command as it is processed currently.