Covers lessons 10...19 for a first pass
1: Estonian references start always with lowercase letters (except names)
2: All pronouns are short forms (unless otherwise noted by "long pron.")
3: pronouns are omitted as soon as verb forms uniquely specify the situation
(exceptions are indicated by "expl.pron.")
4: Colons are always omitted
Upgrade Course I contains the remaining forms up to Unit 13. Units 14 through 30 are found in Upgrade II.