DocProps plugin incorrect case handling of META element names

[NicHolt]

docprops.js creates a hash table of meta elements, keyed by the name converted to lower case. However, there are several cases of tests such as:

name in hash

which fail if the meta element name is not all in lower case. Fix is to replace several occurrences of the above with:

name.toLowerCase() in hash

Also in setupMeta:

result = ( name.toLowerCase() in hash ) ? hash[ name.toLowerCase() ].getAttribute( 'content' ) || '' : '';