Add zip_ftell.

NEWS.md

diff --git a/NEWS.md b/NEWS.md
index 7891f53..627f9e3 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -4,6 +4,7 @@
 * Support legacy zip files with >64k entries.
 * Fix seeking in zip_source_file if start > 0.
 * Add zip_fseek() for seeking in uncompressed data.
+* Add zip_ftell() for telling position in uncompressed data.
 
 1.1.3 [2016-05-28]
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