overlays)

issue #46 solved

there are two type of overlay colors:
* user scope (every user account have custom color schema)
* system scope used when user colors are not defined

classes renamed to species (there are no aliases anymore)
database data about annotators cleared

model-command, graphics and pathvisio converter in progress

model refactoried, celldesigner parser passes tests

the rest stil to be done

classes for all species