SI-9492 REPL paste here doc

Simple here documentish syntax for REPL paste.

This makes it easier to paste a block of script
(as opposed to transcript).

It also means you won't accidentally ctl-D out
of the REPL and then out of SBT and then out of
the terminal window.

```
scala> :paste < EOF
// Entering paste mode (EOF to finish)

class C { def c = 42 }
EOF

// Exiting paste mode, now interpreting.

defined class C

scala> new C().c
res0: Int = 42

scala> :paste <| EOF
// Entering paste mode (EOF to finish)

  |class D { def d = 42 }
EOF

// Exiting paste mode, now interpreting.

defined class D

scala> new D().d
res1: Int = 42

scala> :quit
```

0 files changed, 0 insertions, 0 deletions