HPCC-8030 Java/Python/Javascript language support in ECL

Reworked python embed manager to support functions, imports, etc.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-8030 Java/Python/Javascript language support in ECL

Added java import plugin, and further cleanup on the others

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>