-remove "SIMD" option from "compile_wasm.py" (new Emscripten hasn't that option)

-removed some unnecessary variables
-started C-API implemantation:
 * added C-API option to Meson (build included to main library)
 * refactored some code (moved some code form templates to final code, removed delegates from system)
 * moved templates outside EntityManager to make it possible to use in different functions

demos/compile_wasm.py

@@ -75,7 +75,7 @@ for arg in sys.argv[1:]:
     elif(arg == '-opt'):
         shared_flags += '-O3 '
         ldc_flags += '-release -enable-inlining '
-        emc_flags += '--llvm-lto 3 -s SIMD=1 '
+        emc_flags += '--llvm-lto 3 '
     elif(arg == '-quiet'):
         emc_flags += "-Wl,--no-check-features "
     elif(arg == '--clean'):