Output formatting part should be separated from core logic

[dakusui]

Currently output formatting logic is embedded into core testing logic and not pluggable.
This should be separated from the core logic and pluggable.

[dakusui]

The pluggable logic to output log/report is implemented but remains untested.
It will be included in the next (next after the next) release.

[dakusui]

This will not be fixed. Because I have decided the report output should happen outside JCUnit.