Also changed an exception type in Context. git-svn-id: https://sfml.svn.sourceforge.net/svnroot/sfml/branches/sfml2@1602 4e206d99-4929-0410-ac5d-dfc041789085
git-svn-id: https://sfml.svn.sourceforge.net/svnroot/sfml/branches/sfml2@1600 4e206d99-4929-0410-ac5d-dfc041789085
git-svn-id: https://sfml.svn.sourceforge.net/svnroot/sfml/branches/sfml2@1598 4e206d99-4929-0410-ac5d-dfc041789085