don't highlight anymore for long lines

Fix for Issue #36 "Brackets of different types matched"

* use a nicer variable name

* reuse $pos instead of using another variable
* remove declaration forgotten in last commit

Fix for Issue #35 "Unclosed brackets not marked as error"

* Allow to override highlighters directory through `ZSH_HIGHLIGHT_HIGHLIGHTERS_DIR`
* Handle spaces in the directory path
* Use Zsh builtin "h" modifier instead of `dirname`

Error: "unrecognized modifier 'A'" on startup for zsh 4.3.9 on OSX

Much easier and less error prone way to start highlighting immediately af

Conflicts:
	zsh-syntax-highlighting.zsh

* 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

Originally, zsh-syntax-highlighting called highlight functions at every inputs.
It's OK for user's keyboard inputs. But when long inputs come from clipboard,
it cause noticeable slowdown.

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

The script still works on its own, highlighters in highlighters/ are
loaded as addons if present.

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

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

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

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

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

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

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