API changes -> bump version to 4.6

CHANGELOG.txt

+4.6.0 (Work-in-progress):
+
+* Incompatible API changes: new argument to mesh/getBasisFunctions, removed
+  mesh/preallocateBasisFunctions and mesh/precomputeBasisFunctions.
+
 4.5.6 (March 30, 2020): better calculation of OCC bounding boxes using STL; API
 tutorials; small bug fixes.
 

CMakeLists.txt

@@ -101,8 +101,8 @@ opt(WRAP_PYTHON "Enable generation of Python wrappers for private API" OFF)
 opt(ZIPPER "Enable Zip file compression/decompression" OFF)
 
 set(GMSH_MAJOR_VERSION 4)
-set(GMSH_MINOR_VERSION 5)
-set(GMSH_PATCH_VERSION 6)
+set(GMSH_MINOR_VERSION 6)
+set(GMSH_PATCH_VERSION 0)
 set(GMSH_EXTRA_VERSION "")
 set(GMSH_EXTRA_VERSION_TEXI "${GMSH_EXTRA_VERSION}")