Let resource extensions be listed in a lowercase

[evshvarov]

Currently, when we list resources, the extension should be in upper case. E.g.:

<SourcesRoot>src/iris</SourcesRoot>
      <Resource Name="dc.one.PKG"/>
      <Resource Name="dc.one.INC"/>

but this is a strange rule, as soon as all files are in lower case. Make the possibility to have it in lower case too, or at least the same as in the file name.

[daimor]

Don't get what it's about exactly? Is it still an issue?