Added ETransliterator wrapper object.

Exposes a C api to the transliterator service separately from
the ECollator API.
EBookQuery: Added transliteration queries.

Transliterated queries come in the regular IS, CONTAINS, BEGINS_WITH and
ENDS_WITH variations. They will transliterate the query input and the
fields which they are testing all into Latin script, so that queries
are script insensitive as much as possible.
EBookBackendSexp: Support new transliterated query types.
EBookBackendSqliteDB: Handle new transliterated queries.

For now transliterated normalized strings are not stored in the summary,
just fallback on EBookBackendSexp for these queries.
test-client-custom-summary.c: Added tests for transliteration queries.

Added new vcard 'custom-12.vcf' with chinese words in the full name as well.