#131: Introduce 'modify' to adjust historical records to fixed date/time.

This change introduces a new command that, like lengthen, move, resize, and
shorten, is intended to move and/or resize a record, but instead of taking an
interval, will take an absolute date/time.

This command is useful because it removes the need for the user to calculate
the time intervals to shorten / lengthen a record by. For example, if the user
accidentally forgot to stop tracking an interval before starting a new one,
but new they stopped working at a specific time, it is easy to simply modify
the end time of the interval that they had forgotten to stop.

src/commands/CMakeLists.txt

@@ -21,6 +21,7 @@ set (commands_SRCS CmdAnnotate.cpp
                    CmdHelp.cpp
                    CmdJoin.cpp
                    CmdLengthen.cpp
+                   CmdModify.cpp
                    CmdMove.cpp
                    CmdReport.cpp
                    CmdResize.cpp