[Issue2281] The core.Logger#setLevel method should work like Configurator#setLevel()

[garydgregory]

Do for this module what we did for log4j-1.2-api.

[garydgregory]

Note that the new test fails... @ppkarwasz

[ppkarwasz]

Are we testing the right thing? Unless I am mistaken JUL's Logger#getLevel returns the explicitly configured level of the logger. A call to Logger#setLevel should not change the explicit level of any other logger, but it should change the effective level of all its children.

Unfortunately the effective level can be only be guessed by calling Logger#isLoggable multiple times.

I think that our CoreLogger implementation has an additional bug: it does not overwrite Logger#getLevel. So if a user changes the level of a logger through Log4j Core directly, CoreLogger will not be able to detect it.

[garydgregory]

Ah, good point on the tests, I updated the tests to use isLoggable() and now they pass.

[ppkarwasz]

LGTM

[garydgregory]

LGTM

@ppkarwasz
TY for your help; merged!