Use getCanonicalName rather than getName when emitting source, by principle.

While we only call getName() on top-level class, getCanonicalName is more
accurate when we want the source name rather than the binary name.
Remove redundant code re. finding no-args constructors.
Report error at codegen when child module is missing @Module annotation

It previously failed with an NPE.
Also adds a test for the reflective backend.
Merge pull request #150 from tbroyer/fix-npe-in-fullgraphprocessor

Report error at codegen when child module is missing @Module annotation
Fix integration test: add missing invoker.properties
Nit-picking, following IntelliJ IDEA suggestions.
Merge pull request #152 from tbroyer/fix-it

Fix integration test: add missing invoker.properties
Merge pull request #151 from tbroyer/nitpicking

Nitpicking / code cleanup