Added terms for reactor typ description

[HendrikBorgelt]

Added terms for reactor typ description.

These terms where added:

reactor type
plug flow reactor
stirred tank reactor
tubular reactor
coiled tubular reactor
continously stirred tank reactor
discontinous stirred tank reactor

[dalito]

Another concept in this family:

• Ideal reactor - An abstract concept for a reactor which can be exactly characterized by simplified model equations for mass, momentum and energy.

Regarding the submission:

• I suggest replacing "archetype" by "abstract concept". I could not find chem. eng. references where "archetype" was used in connection with reactor types.
• Please check your defs for typos
• Please don't repeat the preferred label of the concept in the definition text. This is to make the definition independent of the preferred label.