Reorganize vim plugin settings

Setting everything during PlugLoad function caused some plugins to
misbehave. Plugins are now loaded by Plug and their settings can be
either set with a file in the plugin directory (this mimicks the old way
of setting plugin up during load) or in after/ directory, which sets
options *after* everything has loaded.

nvim/.config/nvim/plugin/vim-go.vim

@@ -0,0 +1,25 @@
+" PLUGIN: vim-go
+" change the tabstops for go to use tabs and a width of 4
+" this conforms with the gofmt expectations
+au FileType go set noexpandtab
+au FileType go set shiftwidth=4
+au FileType go set softtabstop=4
+au FileType go set tabstop=4
+" enable all sorts of highlighting options for
+" variables/functions/arguments...
+let g:go_highlight_build_constraints = 1
+let g:go_highlight_extra_types = 1
+let g:go_highlight_fields = 1
+let g:go_highlight_functions = 1
+let g:go_highlight_methods = 1
+let g:go_highlight_operators = 1
+let g:go_highlight_structs = 1
+let g:go_highlight_types = 1
+" enable highlighting of other uses of the same variable
+let g:go_auto_sameids = 1
+" automatically import needed dependencies
+" TODO do I need this? not doing it automatically does lead to more conscious
+" decision making on imports
+let g:go_fmt_command = "goimports"
+" show type information for variables in the status line
+let g:go_auto_type_info = 1