Add second standard <orth> element to lemma for USCB orthography with tones

[iljackb]

1. Make template for new entries include second <orth>: <orth xml:lang="mix" notation="ucsb-tones">

            <form type="lemma">
               <orth xml:lang="mix">tivixi</orth>
               <orth xml:lang="mix" notation="ucsb-tones">tívìxì</orth>
               <pron notation="ipa" xml:lang="mix"></pron>
            </form>

2. Add empty <orth xml:lang="mix" notation="ucsb-tones"/> in each entry that doesn't have it yet and add later