[log] Rename log package to dlog

[at15]

The main reason is gommon/log does NOT have package level methods to log with default config.
So most time in pkg.go I have the following code

import (
    dlog "github.com/dyweb/gommon/log"
)

var logReg = dlog.NewRegistry()
var log = logReg.Logger()

To avoid the rename during import, we can just rename the package because log is used more often, while the logger of gommon/log is a drop in replacement for many logging libraries, the library itself is not. This is also why we use errors instead of derrors. The d prefix from dyweb

It will break all the application/dependencies that depend on it, but AFIK there is no third party library or application using gommon/log