when quitting the bufexplorer window using the 'q' mapping, switch to
the previously active buffer rather than the first buffer in the list
also, preserve the correct alt buffer so that <C-^> works.
Merge branch 'master' of https://github.com/halfmanhalffish/bufexplorer into add_toggle

# By halfmanhalffish
# Via halfmanhalffish
* 'master' of https://github.com/halfmanhalffish/bufexplorer:
  when quitting the bufexplorer window using the 'q' mapping, switch to the previously active buffer rather than the first buffer in the list also, preserve the correct alt buffer so that <C-^> works.