Bump version to 10.6.0.0a1

Author: johnhaddon

Changes

@@ -1,5 +1,5 @@
-10.x.x.x (relative to 10.5.x.x)
-========
+10.6.0.0a1 (relative to 10.5.15.1)
+==========
 
 Fixes
 -----

SConstruct

@@ -58,7 +58,7 @@ ieCoreMilestoneVersion = 10 # for announcing major milestones - may contain all
 ieCoreMajorVersion = 6 # backwards-incompatible changes
 ieCoreMinorVersion = 0 # new backwards-compatible features
 ieCorePatchVersion = 0 # bug fixes
-ieCoreVersionSuffix = "" # used for alpha/beta releases. Example: "a1", "b2", etc.
+ieCoreVersionSuffix = "a1" # used for alpha/beta releases. Example: "a1", "b2", etc.
 
 ###########################################################################################
 # Command line options