Include cmath in example. Fixes #66.
Add SONAME. Fixes #65.
example: replace arial with a free font

Arial is a proprietary font and cannot be included in another package in
distributions like Debian. Replaced it with Liberation.
example: fix compilation command
add CMAKE_INSTALL_LIBDIR

Keeps the default to 'lib', while allowing to use it like so:

-DCMAKE_INSTALL_LIBDIR=lib/x86_64-linux-gnu
Merge pull request #70 from jpleau/libdir

add CMAKE_INSTALL_LIBDIR
Merge pull request #69 from jpleau/examples

example: typo in compilation command, replace arial with a free font
Don't use dereference operator in events example
Merge pull request #72 from eco/patch-1

Don't use dereference operator in events example
Added CMake Find_Package script and debug suffix

* This allows easy inclusion of EntityX in CMake projects using
`Find_Package(EntityX)`.
* Also debug versions now use the `-d` suffix, no longer overwriting
release builds (e.g. `entityx-d.lib` rather than `entityx.lib`).
Merge pull request #73 from MarioLiebisch/cmake-additions

Added CMake Find_Package script and debug suffix