rima: first checkin
rima: updating makefile
rima: updated the makefile to maybe work better on windows.
rima:replaced expression.evaluate with rima.E
rima: functions accept strings in their argument list - they get turned into references.
rima: moved tabulate into values, and made it take arguments the same way as functions.
rima: tidied docs a little
rima: add to docs that function arguments can be strings
rima: you create a function with rima.F rather than rima.func now.
rima: fix up errors messages when checking function arguments.
rima: add rima/tabulate.lua.  Oops, that should have been there...
rima: fixed up docs about tabulate.
rima: sum now takes arguments the same way as rima.F and rima.tabulate
rima: changed the internal workings of sets to prepare for more improvements.
rima: rima.E uses xpcall and debug.traceback
rima: object.isa checks its metatable argument
rima: split iteration stuff out from rima.lua into rima/iteration.lua
rima: more work on iterators - slowly getting there...
rima: started moving tests out into a separate directory.
rima: moved object's tests out into the test directory.