Use <leader>e to map to mkbuild#DmenuOpen('e'). Remove other
conflicting <leader>e mappings:
* <leader>e[x] mappings for various open methods. I generally just use
the '-' mapping to netrw. Although open in a new split might be
handy, I've never used it so far.
* <leader>e mapping for EasyMotion. There isn't that much value in
* <leader>e when <leader>w is available.