* cmd/geth: more testcases for logging
This adds more edgecases around logging, particularly around handling of different types of nil-values
as concrete types and within interfaces.
Also adds tests with 'reserved' values which breaks json/logfmt formats. The json output is checked in,
but not actively used by any testcase at the moment.
* cmd/geth/testdata: remove timestamps
b77a9b127c