Cache taglist() results. Add flush hook.

Fixes #87
Update docs, copyright year ranges
Merge branch 'artnez/tag-scanner-cache' into next

* artnez/tag-scanner-cache:
  Update docs, copyright year ranges
  Cache taglist() results. Add flush hook.
Consider 'autowriteall' when determining default open command

Like `'hidden'`, `'autowriteall'` makes it safe to abandon buffers with
unsaved changes, so we can issue a standard `:e` command in this case
and let Vim save modified files for us beforehand.

Note that we have to include a check to ensure that `'readonly'` isn't
set, because that would prevent `'autowriteall'` from doing its thing.

Fixes:

  https://github.com/wincent/Command-T/issues/88
Make selection acceptance commands configurable
Update HISTORY section in docs
Update docs with info about selection acceptance command configuration
Merge branch 'gnab/configurable-acceptance-commands' into next

* gnab/configurable-acceptance-commands:
  Update docs with info about selection acceptance command configuration
  Make selection acceptance commands configurable
Update Git .mailmap file

To consolidate authorship info as emitted by `git shortlog -s`.
Implement ctrl-w

Originally submitted as:

  https://github.com/wincent/Command-T/pull/11

Changes:

- rebased and fixed merge conflicts (for example, the changes to
  plugin/command-t.vim actually needed to be applied to
  autoload/commandt.vim)
- use `list_matches!` instead of `list_matches` (necessary because
  input debouncing was added since the original submission of the pull
  request)
Add Kevin Webster to Git .mailmap file
Update docs with info about <C-w> feature

- add Kevin Webster to AUTHORS list
- document option for configuring the mapping
  (`g:CommandTClearPrevWordMap`)
- update HISTORY section
Tweak word clearing to match shell behavior

The word clearing algorithm was clearing either words or whitespace. For
example, given the following (where ^ indicates the cursor position):

  foo      bar     baz
                      ^

Hitting <C-w> three times would first delete "baz", then the whitespace
after "bar", finally "bar" itself.

This commit changes the behavior to match that of the shell:

  foo bar
              ^ (<C-w> deletes trailing whitespace and "bar")
  foo       bar
        ^ (<C-w> deletes "foo" and whitespace to left of cursor)
  foobar
     ^ (<C-w> deletes "foo")
  foo
  ^ (<C-W> does nothing)

For clarity and simplicity, switched to a largely regex-based approach
which has no conditionals in it and is probably more readable.
Merge branch 'rabidpraxis/implement-ctrl-w' into next

* rabidpraxis/implement-ctrl-w:
  Tweak word clearing to match shell behavior
  Update docs with info about <C-w> feature
  Add Kevin Webster to Git .mailmap file
  Implement ctrl-w
Change a `#each` + `#<<` to a `#map`

Map better represents our intentions here, so use it.
Clear statusline upon closing the match window

Originally submitted at:

  https://github.com/wincent/Command-T/pull/51

Relevant comment from the discussion:

  Had a closer look at this. This can only be reproduced under very
  specific circumstances: when running Vim in a 256 color terminal
  within tmux using a color scheme that uses a non-black background
  color the statusline never clears unless this patch is applied. For
  example, using using wombat256 or gruvbox
Update HISTORY section in docs
Merge branch 'ton/clear-statusline' into next

* ton/clear-statusline:
  Update HISTORY section in docs
  Clear statusline upon closing the match window
Ensure CommandT::MRU is defined

Even if the extension isn't compiled, we want/need CommandT::MRU to be
defined otherwise our autocommands will blow up as reported here:

  https://github.com/wincent/Command-T/issues/92

I don't particularly like how subtle/brittle this is (the implicit order
dependency), but for now this minimal fix will have to do.

There is still something else going on with issue #92; waiting on
further information about there.
Update HISTORY section of docs

To include info about commit 2f6e86520c5e.