Make space delimiter an option on a per language basis

[alerque]

Right now we have a global preference for using spaces after delimiters:

let g:NERDSpaceDelims = 1

I would like to overhaul this such that each language in our array of supported file types specifies a default integer number of spaces.

Example:

let s:delimiterMap = {
    \ 'aap': { 'left': '#', 'spaces': 1 },
  \}

This would make it easier to manage the cases where some language have stringent style guides, others even mandate spaces for proper lexing, while many people prefer no spaces at all. Additionally it keeps our current "uncomment" code resilient to variations in these preferences, something hard coding the space into the delimiter ruins.

See also #328, #278, #202, #183, #420, #96.

[alerque]

This idea can probably be expanded to other settings such as default alignment (see e.g. this comment for a use case).