Thank's to acieroid.

Applied a modified version of raylu's patch. One can enable/disable wrap-around
scrolling with `set scroll_wrap 1/0". It's disabled per default.

Thanks to Strom

Closes #30

Thanks to thorsten

Add __attribute__((noreturn)) to out_of_memory if supported by the compiler
(gcc, icc and clang).

* Protect LENGTH with surrounding parantheses.
* Use foo(void) for functions taking no arguments.
* Remove dead assignments.

Thanks to kaworu.

Somes fixes for memory related issues. Makes filename and password handling more
robust.

This could be a solution for #6 but needs some testing first.

This is highly experimental but should work in principal. If there is a better
way to dump the contents of stdin to a temporary file, send me a patch, please.

Use XDG_* environment variables to locate the config directory and data
directory. Uses ~/.config/zathura and ~/.local/share/zathura as fallback (the
directories specified in config.h's CONFIG_DIR and DATA_DIR respectively) if the
environment variables are not set.

Uncomment the ZATHURA_NO_XDG define in config.h to always use CONFIG_DIR and
DATA_DIR.

One can specify --config-dir and --data-dir to overwrite the precomputed config
and data location.