Finish conversion to custom elements

[Malvoz]

Elements that are void elements in HTML but which were converted to non-void custom elements (e.g. <meta> => <map-meta></map-meta>) don't always have closing tags, compare:

experiments/datacube/msi-tiles.mapml

Line 4 in cf534fa

<map-meta charset="utf-8"/>

experiments/change-projection/projection-negotiation/msi-osmtile.mapml

Line 4 in cf534fa

<map-meta charset="utf-8"></map-meta>

Using Maps4HTML/MapML.js#515 as a source of truth I believe they should all have closing tags
(</map-(meta|link|input)>). @prushforth can you confirm this?

Elements in other files such as i18n/rtl/restaurants.mapml were not changed in #61 and need to be converted too.

[Malvoz]

(I think the answer lies in that custom elements can't be void elements)

[prushforth]

Autonomous custom elements can't be void elements, and in the HTML configuration of a document (i.e. what we call "inline" MapML within a <layer-> inline mapml </layer-> element, I believe there is no self-closing element syntax in HTML, so we should try to use <map-(meta | link | input)> as required. When accessed via a <layer- src=" URL to MapML document"></layer->, I don't think it makes any difference to the XML parser, so it should not matter too much. However, I discovered that the HTML parser is being used on MapML documents due to the fact (if they in fact are) that they are tagged as belonging to the HTML namespace, for example this URL should be parsed with the XML parser (it's returned with the Content-type: application/xml header) but it is not, due to the use of the xHTML namespace which seems to override the header due to browser sniffing.