lihaoyi/Ammonite

…-stuff

Don't print things marked as private

Previously, private things were printed back, even though they can't be
used after the input block they're defined in, like
```scala
@ private val x = 2; val y = x + 1
x: Int = 2
y: Int = 3
@ x
cmd1.sc:1: not found: value x
val res1 = x
           ^
Compilation Failed
```

This commit changes that, not printing any private thing, like
```scala
@ private val x = 2; val y = x + 1
y: Int = 3
```

This partly reverts some changes of 84d4854, by saving / restoring tty
stuff right before and after reading input. This basically runs
processes right before and after reading input, which incurs a perf cost
- just like before 84d4854.

One can see it by starting an Ammonite session, waiting for it to be
fully started, then repeatedly entering Enter. There's a small delay
between each prompt. 84d4854 addressed that, but breaking a few stuff
along the way (#920, #922).

It wasn't fine after 4a58080. The integration tests still passed as
the launcher file name ends with `.jar` there, and canBeOpenedAsJar
isn't called in that case.

…-url

Allow non-files in classpath

Co-Authored-By: Atry <pop.atry@gmail.com>

when using Ammonite as a library

In particular, this allows to print nothing at all for types other than
Unit.