EBookClientCursor: Enhancing API documentation.

Added a link to EBookClientCursor to include the cursor-example.c
sources directly in the cursor documentation.
EBookBackendSqliteDB: Support transliterated queries for multi-value contact fields.
test-client-custom-summary.c: Added test for transliterated queries

The new test tests that transliterated queries work on the multi valued
fields, specifically we are testing it with E_CONTACT_EMAIL and a
contact containing chinese text.