Bump version to 10.4.0.0a6 and update Changes

Author: johnhaddon

Changes

@@ -1,3 +1,25 @@
+10.4.0.0a6 (relative to 10.4.0.0a5)
+==========
+
+Improvements
+------------
+
+- USDScene : Added support for reading and writing purpose-based material bindings (#1273).
+- IECoreGL::Shader : Added support for buffer samplers (#1264).
+- Adopted stricter default compilation flags (#1266).
+
+Fixes
+-----
+
+- PointDistribution : Fixed inconsistent distributions between MacOS and Linux. The Linux distribution is now used on all platforms (#1269).
+- Fixed compilation with C++17 (#1269, #1265).
+- IECoreGL : Fixed build errors on MacOS (#1271).
+
+Breaking Changes
+----------------
+
+- PerlinNoise/Turbulence : Removed. We recommend OpenShadingLanguage's `liboslnoise` instead (#1269).
+
 10.4.0.0a5 (relative to 10.4.0.0a4)
 ==========
 

SConstruct

@@ -58,7 +58,7 @@ ieCoreMilestoneVersion = 10 # for announcing major milestones - may contain all
 ieCoreMajorVersion = 4 # backwards-incompatible changes
 ieCoreMinorVersion = 0 # new backwards-compatible features
 ieCorePatchVersion = 0 # bug fixes
-ieCoreVersionSuffix = "a5" # used for alpha/beta releases. Example: "a1", "b2", etc.
+ieCoreVersionSuffix = "a6" # used for alpha/beta releases. Example: "a1", "b2", etc.
 
 ###########################################################################################
 # Command line options