Merge pull request #49 from vh21/tweak-dbg

Refine debug I/O facilities
Kconfig: tweak debug options
reorder initial routines by utilizing init hooks

Fixes #47

Signed-off-by: Jim Huang <jserv@0xlab.org>
correct configuration dependency of tickless compensation
mk: adjust Kconfig entries with explicit classification

The build configurations should be specified by Kconfig in each
directory rather than the definitions in file mk/Config.in, which is
going to semi-retire by reducing its functionality.
add DreamLinuxer in author list
exclude *~ for .gitignore
debug: tweak debug device configurations

1. remove source when no debug device exists
2. tweak function prototype

Signed-off-by: Viller Hsiao <villerhsiao@gmail.com>
debug: add function to change debug device

Signed-off-by: Viller Hsiao <villerhsiao@gmail.com>
debug: add a simple ram debug device implementation

Signed-off-by: Viller Hsiao <villerhsiao@gmail.com>