tee(1) truncated $fname.  Fortunately, the data that got truncated had just
been `git add`-ed, so no harm was done.

Currently, without zsh/zle loaded, the tests silently fall back to the
5.2-and-earlier codepath; see:
.
    https://github.com/zsh-users/zsh-syntax-highlighting/pull/356#issuecomment-243651251

Use correct indexing also for cursor-matchingbracket.

Fixup for 95d82568d8

Since the _zsh_highlight_add_highlight that the tests use ignores
ZSH_HIGHLIGHT_STYLES, we can test both an injective mapping and an empty
mapping at once.

All these files should be sourced, not executed; and Debian's lintian complains:

W: zsh-syntax-highlighting: script-not-executable usr/share/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh

Fixes issue #195.

* Don't override user defined styles
* Better modularisation of highlighters
* Allow to define which highlighters are activated
* Allow to define the order in which they are defined
* Minor performance optimizations
* Fixed some variables leak
* Improve documentation
* Brackets highlighter: use ZSH_HIGHLIGHT_STYLES instead of a specific array

Feel free to add more test data !

Signed-off-by: Julien Nicoulaud <julien.nicoulaud@gmail.com>