tornado: add logic for when tornado runs out of steam

This is code from the original C/C++ release, modified to fix
what I perceived as a bug. After the tornado runs for 200 ticks,
there is a 0.2% chance of termination each tick.

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@912 d9718cc8-9f43-0410-858b-315f434eb58c
tools: define size/cost of tool as regular properties of the tool

rather than using a giant switch block to determine size/cost

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@913 d9718cc8-9f43-0410-858b-315f434eb58c
tools: define default tool colors

so that colors do not need to be explicitly specified every time
a new tool is defined.

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@914 d9718cc8-9f43-0410-858b-315f434eb58c
tools: make translation strings optional for tools

If a translation string is not defined for the tool name, icon name,
or tool description, then an automatic string is generated.

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@915 d9718cc8-9f43-0410-858b-315f434eb58c