Add new `Language` snippet property

[delphidabbler]

A new snippet key named Language would be useful to enable users to add snippets of any language.

At a minimum the following would be needed:

• pascal
• none

Other popular languages could be added.

The default language to be used when Language is not specified should be none, with the ability for collections to override in the config file.

As an alternative to having to specify all permissible languages in the collection specs, could the user list the languages in the config file:

SupportedLanguages=c++,javascript,perl

If this is done though needs to be given as to whether pascal and none are always defined.

One solution could be to use a * language name in the list to mean "include all defaults", so that:

SupportedLanguages=rust,*

is equivalent to

SupportedLanguages=rust,pascal,none