minor, memmove() lstk items less often

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, provide position sub-command

position is what Rudi needs, given a date or time and a file with trod directives
output a list of invested contracts in echs format.

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
test, provide some regression tests for position command

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, allow co_echs_rdr to read lines with just a date/time and no separator

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'cmd/position'

* cmd/position:
  minor, allow co_echs_rdr to read lines with just a date/time and no separator
  test, provide some regression tests for position command
  minor, provide position sub-command
  minor, memmove() lstk items less often