Update README.md

Added details of requirements for compiling
Update README.md

Added details of requirements for compiling
Merge branch 'master' of git@github.com:LupusUmbrae/map.git
Code merged back to master. All headers documented and redundant method
declarations removed.
#12 Json usage extracted to seperate class

MapTexture now has common code to convert from surface to texture, this
also adds the texture to the loadedTextures vector
Documentation updated
Additional doxygen docs added
#13 a somewhat unsafe and pretty poor input dialog box now works
Log message removed
#8 now able to scroll slightly outside the max area and see the map
border.
#8,#9,#14 Scaling and scrolling issue now fixed