Bump version to 4.0
Delete CHANGES.txt
Remove deprecated APIs
Remove SAMPGDK_USE_NAMESPACE, always use namespace
Remove AMX and SDK headers
Remove sampgdk_get_plugin_data()
Remove trailing spaces
Rewrite CMake find module
Find SA-MP SDK via FindSDK module
Return back AMX intefacing code
Place all SDK stuff in one header

Merge amx.h and plugin.h into one file - sdk.h. This is noy only
convenient, but may prevent subtle include errors because of the
files with exactly the same names in src/ (src is currentl added
to include path).
Move C++ code back to .h files
Export sampgdk_(v)logprintf as functions
Auto detect calling plugin in sampgdk_process_timers()

Process only those timers that belong to the calling plugin using same
techniques as in sampgdk_init(). This avoid extra overhead when running
many plugins at once.
Introduce SAMPGDK_API and SAMPGDK_DEPRECATED_API
Fix inconsistent DLL linkage warning
Prevent redefinition of export macros
Replace SampPlugin with new Plugin module
Fix heap array not being padded on resize (issue #57)

Conflicts:
	src/fakeamx.c
Remove duplicate assert