Clean up project structure

Split the monolithic 'stirling' project into three subprojects:

  - 'stirling-core'
  - 'stirling-fix-console'
  - 'stirling-fix-perftest'

While at it, rename the FIX console to 'fix-console.jar', use
'sbt-start-script' for the FIX performance test, and remove IDE
cruft for Eclipse and IntelliJ IDEA.

Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>
Update package name in documentation

Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>