Modularize main application code

[tuxalp]

Modules and packages are common python concepts to organize application code.

This "issue" suggests to make use of these concepts to more cleanly separate "responsabilities" of the application, like:

• ojpfare api
• nova client
• ojp1 client
• ojp2 client
• tests

Currently only these modules exist:

• api
• nova (generated code added to git)
• ojp (generated code added to git)
• ojp2 (generated code added to git)

Some other directories exist that are not python code:

• logs
• service
• xslt

Servers and other packages reside in the plain project root, not in a module.

See also here for a description of directories:
https://github.com/openTdataCH/ojp-nova/blob/master/docs/file_structure.md

Proposal for new modules tree:

Module	Description
app	Main application module with servers
app.api	Hosts API , request/response handling including error handler
app.ojpfare1	Business logic implementing ojpfare v1
app.ojpfare1.ojp	Business logic implementing trip request of ojpfare v1 map_ojp_to_ojp (?)
app.ojpfare1.ojp.xsdata	xsdata generated py-files for ojp1
app.ojpfare1.fare	Business logic implementing fare request of ojpfare v1 map_nova_to_ojp map_ojp_to_nova
app.ojpfare2	Business logic implementing ojpfare v2
app.ojpfare2.ojp	Business logic implementing trip request of ojpfare v2 map_ojp_to_ojp (?)
app.ojpfare2.ojp.xsdata	xsdata generated py-files for ojp2
app.ojpfare2.fare	Business logic implementing fare request of ojpfare v2 map_nova_to_ojp2 map_ojp2_to_nova
app.nova	Client for NOVA Preisabfrage
app.nova.xsdata	xsdata generated py-files for NOVA
test	Packages used for testing only. Test packages may also go to according modules they test, e.g.: test_client.py to app.ojpfare1.ojp.