Use 1.0.0 as shared library version on the v2 branch.

This way we can add a 0.0.0 for the v1 branch.
diff --git a/SConstruct b/SConstruct
index 72e688e..607dd5f 100644
--- a/SConstruct
+++ b/SConstruct
@@ -16,7 +16,7 @@
 env.Replace(CXX = ARGUMENTS.get('CXX', 'g++'))
 
 # for shared lib, requires scons 2.3.0
-env['SHLIBVERSION'] = '0.0.0'
+env['SHLIBVERSION'] = '1.0.0'
 
 CCFLAGS = []
 if int(debug):