Fix byte compiler warnings

[twmr]

There are a bunch of warnings output by the byte compiler: (using emacs 27.0)

Compiling file /home/thomas/.emacs.d/elpa/dumb-jump-20190204.331/dumb-jump.el at Mon Feb 11 19:32:01 2019
Entering directory ‘/home/thomas/.emacs.d/elpa/dumb-jump-20190204.331/’
dumb-jump.el:70:1:Warning: defcustom for
    ‘dumb-jump-ivy-jump-to-selected-function’ fails to specify type
dumb-jump.el:70:1:Warning: defcustom for
    ‘dumb-jump-ivy-jump-to-selected-function’ fails to specify type
dumb-jump.el:1649:1:Warning: Unused lexical argument ‘proj’
dumb-jump.el:1800:1:Warning: Unused lexical argument ‘config’

In dumb-jump-goto-file-line:
dumb-jump.el:2162:17:Warning: ‘find-tag-marker-ring’ is an obsolete variable
    (as of 25.1); use ‘xref-push-marker-stack’ or ‘xref-pop-marker-stack’
    instead.
dumb-jump.el:2432:1:Warning: Unused lexical argument ‘cur-file’
dumb-jump.el:2481:1:Warning: Unused lexical argument ‘exclude-paths’
dumb-jump.el:2481:1:Warning: Unused lexical argument ‘lang’

It would be nice if they could be fixed.

[jacktasia]

Thanks for opening this!

[jacktasia]

So for the record, I looked into this, and the only ones that will be really easy to fix are the defcustom ones, which I'll do pretty soon, but the rest would require changing public methods and/or shared method signature. This is because when the same piece of code makes the call regardless of searcher so the signature needs to stay the same, but each one of those functions doesn't necessarily use all the passed vars. So I need to think about the best way to do this, but if anyone has any ideas for the best/easiest way to do it. I am definitely open.