Remove `colorscheme_manager#load()`, `xolox#colorscheme_switcher#switch_to()` does everything already.
Make `colorscheme_manager#init()` use `xolox#colorscheme_switcher#switch_to()`.
Make `:BlacklistAddColorScheme`, `:BlacklistRemColorScheme`, `colorscheme_manager#add_blacklist()` & `colorscheme_manager#rem_blacklist()` take an optional argument (colorscheme) to remove/add instead of current, and return 1/0 on success/fail.
Fix a couple more whoopsies with multiline commands.
Add `:SwitchToColorScheme command`, just sugar for `xolox#colorscheme_switcher#switch_to()`.
Fix global variable for last scheme so its actually stored in vimsessions when 'globals' is present in 'sessionoptions'.