Clean up project structure

Split the monolithic 'stirling' projects into three subprojects:

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

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

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