Build improvement and better integration with projectile

- For a malinka project it's now possible to add a compile command which
  will be executed with projectile's compile project and a test command
  which will be executed with projectile's test project functionality

- Projects now have a build and a root directory since they may
  differ. A build directory is the directory from which the build
  command is executed and the root directory should be the root
  directory of the project's files.