Add core.cpp, testing changes

tests/test_table.cpp

@@ -1,5 +1,3 @@
-#include "../core_library/core.c"
-
 void TestSimpleInsertAndIntegrity() {
     MA_Scratch scratch;
     Table<uint64_t> table = {scratch};
@@ -36,9 +34,3 @@ void TestStrings() {
     IO_Assert(table.gets("3")->i == 3);
     table.dealloc();
 }
-
-int main() {
-    TestSimpleInsertAndIntegrity();
-    TestStrings();
-    return 0;
-}