Delete dead NSI installer files

...newview/installers/windows/FILES_ARE_UNICODE_UTF-16LE.txt

indra/newview/installers/windows/install_icon.BMP

indra/newview/installers/windows/installer_template.nsi

indra/newview/installers/windows/lang_da.nsi

indra/newview/installers/windows/lang_de.nsi

indra/newview/installers/windows/lang_en-us.nsi

indra/newview/installers/windows/lang_es.nsi

indra/newview/installers/windows/lang_fr.nsi

indra/newview/installers/windows/lang_it.nsi

indra/newview/installers/windows/lang_ja.nsi

indra/newview/installers/windows/lang_pl.nsi

indra/newview/installers/windows/lang_pt-br.nsi

indra/newview/installers/windows/lang_ru.nsi

indra/newview/installers/windows/lang_tr.nsi

indra/newview/installers/windows/lang_zh.nsi

indra/newview/installers/windows/language_menu.nsi

indra/newview/installers/windows/uninstall_icon.BMP