Update cmake to build on windows

[sourencho]

Description

• Link dependencies to client-lib and server-lib before, in turn, linking them to their executables
  • See the path I took to discover this here: https://en.sfml-dev.org/forums/index.php?topic=27152.0
• Windows build having trouble with uint so I replaced them all with uint32_t
• Add cmake var GUNGROUP_STATIC to statically link sfml and gcc stuff
• Remove redundant -std=c++11 from CMAKE_CXX_FLAGS
• Downgrade boost requirement to 1.55 because I couldn't find 1.65 on windows
• Handle -pthreads in a generic way with CMake's find_package(Threads).

Fixes

Fixes #178

[sourencho]

Hmm, seems like having a static build on linux (and probably also mac) won't be easy. I get the error below when I try to build on this branch. According to the this forum post we'd have to compile sfml to statically link it.

➜  ungroup_game git:(windows_static_link_build) ✗ ./scripts/build.sh
Detected Ninja is installed. Using Ninja.
-- The CXX compiler identification is AppleClang 10.0.1.10010046
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Warning at /Library/Frameworks/SFML.framework/Resources/CMake/SFMLConfig.cmake:103 (message):
  Static frameworks are not supported by SFML.  Clear SFML_DIR cache entry,
  and either change SFML_STATIC_LIBRARIES or CMAKE_FIND_FRAMEWORK before
  calling find_package(SFML)
Call Stack (most recent call first):
  CMakeLists.txt:15 (find_package)

CMake Error at /Library/Frameworks/SFML.framework/Resources/CMake/SFMLConfig.cmake:139 (message):
  Requested SFML configuration (Static) was not found
Call Stack (most recent call first):
  CMakeLists.txt:15 (find_package)

CMake Error at CMakeLists.txt:15 (find_package):
  Found package configuration file:

    /Library/Frameworks/SFML.framework/Resources/CMake/SFMLConfig.cmake

  but it set SFML_FOUND to FALSE so package "SFML" is considered to be NOT
  FOUND.

-- Configuring incomplete, errors occurred!
See also "/Users/peco/Documents/code/ungroup_game/build/CMakeFiles/CMakeOutput.log".
ninja: Entering directory `build'
ninja: error: loading 'build.ninja': No such file or directory