Feature proposal: PlugBisect command for tracking down plugin conflicts

After putting together a new Vim plugin loadout using vim-plug, I've found myself having to bisect several plugin conflicts and do some mixture of reporting them, reconfiguring them, and finding replacements.

Given that "Can review and rollback updates" is in-scope for vim-plug, have you considered an analogue to `git bisect` where the user then repeatedly closes Vim, reopens it, and then reports whether or not the problem is still present?

(The end result being a readout on which combination of plugins is necessary to produce the symptoms without the tedious and potentially error-prone process of manually commenting out `Plug` lines and then restoring them.)

------------------------------

```
:version
VIM - Vi IMproved 8.1 (2018 May 18, compiled Oct 28 2019 12:52:50)
Included patches: 1-2231
Modified by jonathon.fernyhough@york.ac.uk
Compiled by jonathon.fernyhough@york.ac.uk
Huge version with GTK3 GUI. Features included (+) or not (-):
+acl -farsi -mouse_sysmouse -tag_any_white
+arabic +file_in_path +mouse_urxvt +tcl
+autocmd +find_in_path +mouse_xterm +termguicolors
+autochdir +float +multi_byte +terminal
-autoservername +folding +multi_lang +terminfo
+balloon_eval -footer -mzscheme +termresponse
+balloon_eval_term +fork() +netbeans_intg +textobjects
+browse +gettext +num64 +textprop
++builtin_terms -hangul_input +packages +timers
+byte_offset +iconv +path_extra +title
+channel +insert_expand +perl +toolbar
+cindent +job +persistent_undo +user_commands
+clientserver +jumplist +postscript +vartabs
+clipboard +keymap +printer +vertsplit
+cmdline_compl +lambda +profile +virtualedit
+cmdline_hist +langmap -python +visual
+cmdline_info +libcall +python3 +visualextra
+comments +linebreak +quickfix +viminfo
+conceal +lispindent +reltime +vreplace
+cryptv +listcmds +rightleft +wildignore
+cscope +localmap +ruby +wildmenu
+cursorbind +lua +scrollbind +windows
+cursorshape +menu +signs +writebackup
+dialog_con_gui +mksession +smartindent +X11
+diff +modify_fname +sound -xfontset
+digraphs +mouse +spell +xim
+dnd +mouseshape +startuptime +xpm
-ebcdic +mouse_dec +statusline +xsmp_interact
+emacs_tags +mouse_gpm -sun_workshop +xterm_clipboard
+eval -mouse_jsbterm +syntax -xterm_save
+ex_extra +mouse_netterm +tag_binary
+extra_search +mouse_sgr -tag_old_static
system vimrc file: "$VIM/vimrc"
user vimrc file: "$HOME/.vimrc"
2nd user vimrc file: "~/.vim/vimrc"
user exrc file: "$HOME/.exrc"
system gvimrc file: "$VIM/gvimrc"
user gvimrc file: "$HOME/.gvimrc"
2nd user gvimrc file: "~/.vim/gvimrc"
defaults file: "$VIMRUNTIME/defaults.vim"
system menu file: "$VIMRUNTIME/menu.vim"
fall-back for $VIM: "/usr/share/vim"
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -DFEAT_GUI_GTK -pthread -I/usr/in
clude/gtk-3.0 -I/usr/include/at-spi2-atk/2.0 -I/usr/include/at-spi-2.0 -I/usr/incl
ude/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/gtk-3.0 -
I/usr/include/gio-unix-2.0/ -I/usr/include/mirclient -I/usr/include/mircore -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12 -I/usr/include/
gdk-pixbuf-2.0 -I/usr/include/libpng12 -I/usr/include/glib-2.0 -I/usr/lib/x86_64-l
inux-gnu/glib-2.0/include -Wdate-time -g -O2 -fPIE -fstack-protector-strong -Wfor
mat -Werror=format-security -D_REENTRANT -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1

Linking: gcc -L. -Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now -fstack-protec
tor -rdynamic -Wl,-export-dynamic -Wl,-E -Wl,-Bsymbolic-functions -fPIE -pie -Wl,
-z,relro -Wl,-z,now -Wl,--as-needed -o vim -lgtk-3 -lgdk-3 -lpangocairo-1.0 -lpa
ngo-1.0 -latk-1.0 -lcairo-gobject -lcairo -lgdk_pixbuf-2.0 -lgio-2.0 -lgobject-2.0
-lglib-2.0 -lSM -lICE -lXpm -lXt -lX11 -lXdmcp -lSM -lICE -lm -ltinfo -lnsl -ls
elinux -lcanberra -lacl -lattr -lgpm -ldl -L/usr/lib -llua5.2 -Wl,-E -fstack-pr
otector-strong -L/usr/local/lib -L/usr/lib/x86_64-linux-gnu/perl/5.22/CORE -lperl
-ldl -lm -lpthread -lcrypt -L/usr/lib/python3.5/config-3.5m-x86_64-linux-gnu -lp
ython3.5m -lpthread -ldl -lutil -lm -L/usr/lib/x86_64-linux-gnu -ltcl8.6 -ldl -lz
-lpthread -lieee -lm -lruby-2.3 -lpthread -lgmp -ldl -lcrypt -lm
```

- Type:
- [ ] Bug
- [ ] Enhancement
- [x] Feature Request
- [ ] Question
- OS:
- [ ] All/Other
- [x] Linux
- [ ] OS X
- [ ] Windows
- Vim:
- [x] Terminal Vim
- [x] GVim
- [ ] Neovim