Issue #1234 - Remove 'CString' From 'ToLowerString()'

src/plugin/PluginUtil.h

Index: src/plugin/PluginUtil.h
===================================================================
--- a/src/plugin/PluginUtil.h
+++ b/src/plugin/PluginUtil.h
@@ -33,6 +33,7 @@
 
 /**
  * Return a lower-case version of the argument string.
- * Current version uses 'CString::MakeLower()' to preserve legacy behavior during refactoring.
+ * Collates according to the current locale.

[sergei, 2015/12/16 10:32:45]

That seems to be correct choice. We can also create something like
`ToLowerStringCLocale` which we can use to convert HTML tags, for example.

[Eric, 2015/12/16 13:53:26]

For my purposes in this change set, it's the choice that doesn't change the
previous behavior. Right or wrong isn't the question at the moment.

Now, however, its behavior is documented now so that we can make informed
decisions about locale issues in the future.

+ * May not lower-case entire string if it contains embedded null characters.

[sergei, 2015/12/16 10:32:45]

I know that it can theoretically happen, especially because we do store the
entire string while we are converting BSTR which is good, but does it actually
happen and when? 

See the comment for the body.

[Eric, 2015/12/16 13:53:26]

I don't think we ever have a situation where we'll see an input with embedded
null. That said, it's important to document the function as it stands, not how
it's used.

I've changed this specification comment to make fewer guarantees in this
situation.

  */
 std::wstring ToLowerString(const std::wstring& s);