Update changelog

HISTORY

@@ -1,7 +1,8 @@
 amath release history
 
-v1.8.1 May 1 2017
-- OpenBSD support
+v1.8.1 April 22 2017
+- OpenBSD support.
+- Fixed Haiku bug.
 
 v1.8.0 April 13 2017
 - Fixed bugs in numeral systems.

src/main.h

@@ -261,8 +261,9 @@
   \page    release_page Release history
   \section release_sec  Release history
 
-  \subsection version181 1.8.1 May 1 2017
+  \subsection version181 1.8.1 April 22 2017
   - OpenBSD support
+  - Fixed Haiku bug
 
   \subsection version180 1.8.0 April 13 2017
   - Fixed bugs in numeral systems.