support one liners with `#? braces` syntax
1 liners are very useful for REPL, otherwise cmd recall is kind of broken.

braces syntax allow arbitrary nim code to fit in 1 line.

eg:
`>>> proc fun(a:int): auto {return a*2}`

implementation:
using undocumented(?) ``#? braces` syntax 

eg:
foo.nim
```nim
#? braces

proc main() {
  echo "Hello"
}

when (isMainModule) {
  main()
}
```

this mode could be enabled via a meta option, see https://github.com/AndreiRegiani/INim/issues/6,  eg :brace=on or :brace=off