define the names of syntactic parts of OM objects in 2.1.3

[kohlhase]

We often use names for the syntactic parts of the OM objects without really defining them. For instance "binder" is not defined anywhere. I propose to define all of these in 2.1.3 where the syntactic shape of complex OM Objects is first introduced. In particular

• in (ii) application define "function" and "argument sequence" and maybe "n-th argument" (which is the n+1th child.
• in (iii) attribution define "syntactic head" ("head" will be defined with flattening), "key", "attribute value", and "attribute sequence".
• in (iv) binding define "binder", "bound variables", and "body".
• in (v) error define ????? how do we call S and the A_i? And once we have defined these, we can clean up the text below and refer to these definitions via the referencing mechanisms posited in #55

[kohlhase]

I would really like to have the vocab at my disposal when writing about things like alpha-renmaming.

[kohlhase]

I will start on this in the next days (I am skiing and this is the optimal apres-ski occupation).