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

command tests fixed, converter tests fixed and some pathvisio tests
fixed

model-command, graphics and pathvisio converter in progress

model refactoried, celldesigner parser passes tests

the rest stil to be done

classes for all species