Fixed various typos.

Applied patch by snowleopard2 fixing a bunch of typos such as misspellings and double words in the documentation. Combined the patch with some local queued typos waiting to be committed as well as adding new typo fixes inspired by the patch.

Function names with American spelling were not changed nor was third-party code touched. The only code changes involve some changes in strings that are translated ("Can not" -> "Cannot").

Closes #13063 (again).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67280 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/doxygen/overviews/unicode.h

@@ -230,7 +230,7 @@ problems:
   - Using a cast to force the issue (listed only for completeness):
     @code printf("Hello, %s", (const char *)s.c_str()) @endcode
 
- - The result of @c c_str() can not be cast to @c char* but only to @c const @c
+ - The result of @c c_str() cannot be cast to @c char* but only to @c const @c
    @c char*. Of course, modifying the string via the pointer returned by this
    method has never been possible but unfortunately it was occasionally useful
    to use a @c const_cast here to pass the value to const-incorrect functions.