Fix version string comparison, capitalisation and typos.

IPython/extensions/cythonmagic.py

@@ -3,7 +3,7 b''
 The cython magic has been integrated into Cython itself, 
 which is now released in version 0.21.
 
-cf github `cython` organisation, `cython` repo, under the 
+cf github `Cython` organisation, `Cython` repo, under the 
 file `Cython/Build/IpythonMagic.py`
 """
 #-----------------------------------------------------------------------------
@@ -16,6 +16,8 b' file `Cython/Build/IpythonMagic.py`'
 
 from __future__ import print_function
 
+import IPython.utils.version as version
+
 try:
     import Cython
 except:
@@ -34,7 +36,7 b' def load_ipython_extension(ip):'
     print("""The Cython magic has been move to the Cython package, hence """)
     print("""`%load_ext cythonmagic` is deprecated; Please use `%load_ext Cython` instead.""")
     
-    if Cython is None or tuple(map(int,Cython.__version__.split('.'))) < (0,21) : 
+    if Cython is None or not version.check_version(Cython.__version__, "0.21"):
         print("You need Cython version >=0.21 to use the Cython magic")
         return 
     print("""\nThough, because I am nice, I'll still try to load it for you this time.""")

docs/source/config/extensions/cythonmagic.rst

@@ -4,4 +4,4 b''
 cythonmagic
 ===========
 
-The `cython` magic has been moved in the `cython` package.
+The `cython` magic has been moved in the `Cython` package.

docs/source/whatsnew/pr/remove_cythonmagic.rst

@@ -1,1 +1,1 b''
-* The ``%cython`` magic, is now part of the Cython module. Use `%load_ext Cython` with a version of Cython >= 0.21 to have acces to the magic now. 
+* The ``%cython`` magic, is now part of the Cython module. Use `%load_ext Cython` with a version of Cython >= 0.21 to have access to the magic now.