add TODO for non-blocking file events
add missing import
remove unused ProcessPipes and use DMD env
use absolute drepl_sandbox path
add drepl.service systemd script and deploy.sh
fix unittest and add .travis.yml

- Currently needs dmd master because Issue 12144
  is triggered by Dscanner.
add support for multiple statements

- partly fixes #14
test case for multi-line input with single blank line
quickfix to skip comment lines
add test cases for dmd engine
support void expressions
capture stdout, stderr

- also use stdout to output eval results

- return both captures as EngineResult

- use JSON in sandbox output
fix - comments aren't empty lines

- so they shouldn't abort input continuation
fix test

- set DMD env for D REPL
fix output for comma expressions
remove debug comment
use File event to wait for sandbox response

- check process state before reading

- handle invalid process output

- use scope (exit) hook to kill process
send compile errors to stderr