timesequence: add string template system

Gnuplot files as well as all other template files are currently copied
in the output directory without any modification. To extend the format
and add _conditional_ additional information to the GPI file we must
change to content. Via python string.Template class we can simple change
file content. Without any regex magic.

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: refactor code and make variable smaller

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: refactor code - II

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: add PUSH flag visualization

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: add duration calculation

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: support data sender flow

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: re-format init method

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: add color definitions for ECN flags

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: draw ECN flags for DATA (TX) side

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
timesequence: draw ECN flags for ACK (RX) side

Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>