TyInf: minor changes in secs 1-3; reorganise sec 4 to better motivate lemma 1; fix circularity in sec 7.1
TyInf: minor changes in secs 1-3; reorganise sec 4 to better motivate lemma 1; fix circularity in sec 7.1

mietek/epigram2,mietek/epigram2,larrytheliquid/pigit