@Nullable
    private String copyToWherigoFolder(final Uri uri) {
        String filename = ContentStorage.get().getName(uri).replace("_", "-");
        if (StringUtils.isBlank(filename)) {
            return null;
        }
        if (StringUtils.equalsAnyIgnoreCase(filename.substring(filename.length() - 4), ".gwc")) {
            filename = filename.substring(0, filename.length() - 4);
        }
        ContentStorage.get().copy(uri, PersistableFolder.WHERIGO.getFolder(), FileNameCreator.forName(filename + ".gwc"), false);
        return filename;
    }
copy uri to wherigo folder
<br />
For "guid calculation" of WherigoActivity,
- capitalization of suffix ".gwc" will be normalized to ".gwc"
- all "_" will be replaced by "-"
<br />
returns "guid" (= filename without suffix ".gwc") on success, null otherwise
main/src/main/java/cgeo/geocaching/HandleLocalFilesActivity.java