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

search for multiple drugs returned from time to time more results than
queried

connection

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

model refactoried, celldesigner parser passes tests

the rest stil to be done

classes for all species