Bug fixes

Fixed some more mistakes and changed the numbering of theorems, lemmas, corollaries, propositions and definitions to read like this:

Definition 1.1
Proposition 1.2
Definition 1.3
Theorem 1.4
Lemma 1.5
Corollary 1.6
Definition 1.7

Before, definitions, lemmas etc. each had its own counter:

Definition 1.1
Proposition 1.1
Definition 1.2
Theorem 1.1
Lemma 1.1
Corollary 1.1
Definition 1.3