Implement the textual export of FlowConnectionUsages

[adaussy]

Aims to provide the export of FlowConnectionUsage.

For example, il the flashlight tutorial the 3 following FlowConnectionUsage are not properly exported.

...
first start then fork1;

// define input/output flow from the output of one action to the input of another action
flow from provideDCPwr.dcPwr to connectDCPwr.dcPwrIn;
flow from connectDCPwr.dcPwrOut to generateLight.dcPwrIn;
flow from generateLight.light to directLight.lightIn;

...

The current result is:

...
first start then fork1;
action;
action;
action;
...

[adaussy]