It seems there are three approaches to this task;
1 Use your regular full curcuit design/PCB layout tools - DipTrace, Eagle, Express etc etc and either set up templates or simply build wide tracks on the bottom and use the tracks on the top as the links. Set the grid and snap to 0.1"
2. Pay money for something like lochmaster, Veecad, Stripboard designer, etc. It seems unless you pay, components are minimal and you may not be able to create your own. Appearance of the board is an issue also with lochmaster giving a pictorial representation of the components - not just a pattern.
3. Freebies - simplest/easiest I've found so far is a program called VeroDes. This is very basic but allows full component design and seems to do all the things that are needed to simply document a vero(strip)board circuit. It does not have a circuit designer - just allows the board and components to be drawn up. Program is fairly basic but seems to work OK with a 128 x 128 hole maximum.