Move bulk of plugin code to autoload dir to save startup time

[fent]

At 3000 lines, it seems like this plugin would gain a generous improvement in startup time since most of the functionality isn't used. It looks like only the mappings at the bottom of the file are needed, the rest can be moved to an autoload directory.

See :help autoload

[alerque]

I'd be happy to review and accept a PR that accomplishes this.

[Ryuno-Ki]

@alerque Maybe it makes sense to create a new label to indicate, that you would accept PRs. Something like „PR wanted” or so.

[alerque]

@Ryuno-Ki Please don't repeat the same comment more than one place. See here for my response.