Migrate core source files to C++. Add yaml-cpp project as dependency (#2207)

By updating to this commit, Linux users have to regenerate Makefiles by re-running the configure script.

* Added yaml-cpp project as a 3rdparty library
* Migrated source files core to C++
* Updated configure scripts
* Make Linux installations compile *.cpp files
* Made server components' main source file C++
* Also made headers CPP-aware.

* Added basic C wrapper for yaml-cpp library
* YAML-node path is delimited by periods.
* Basic integer types and string are supported.
* Strings returned from this wrapper have to be freed with malloc.h::aFree
* Arrays (sequence) is supported with iterator wrapper.
* Remember to free every wrapper you create!

* Add yaml-cpp as dependency of common project
* Made the repo not ignore *.yml files

Thanks to @aleos89 and @Lemongrass3110.

3rdparty/yaml-cpp/src/parse.cpp

@@ -0,0 +1,72 @@
+#include "yaml-cpp/node/parse.h"
+
+#include <fstream>
+#include <sstream>
+
+#include "yaml-cpp/node/node.h"
+#include "yaml-cpp/node/impl.h"
+#include "yaml-cpp/parser.h"
+#include "nodebuilder.h"
+
+namespace YAML {
+Node Load(const std::string& input) {
+  std::stringstream stream(input);
+  return Load(stream);
+}
+
+Node Load(const char* input) {
+  std::stringstream stream(input);
+  return Load(stream);
+}
+
+Node Load(std::istream& input) {
+  Parser parser(input);
+  NodeBuilder builder;
+  if (!parser.HandleNextDocument(builder)) {
+    return Node();
+  }
+
+  return builder.Root();
+}
+
+Node LoadFile(const std::string& filename) {
+  std::ifstream fin(filename.c_str());
+  if (!fin) {
+    throw BadFile();
+  }
+  return Load(fin);
+}
+
+std::vector<Node> LoadAll(const std::string& input) {
+  std::stringstream stream(input);
+  return LoadAll(stream);
+}
+
+std::vector<Node> LoadAll(const char* input) {
+  std::stringstream stream(input);
+  return LoadAll(stream);
+}
+
+std::vector<Node> LoadAll(std::istream& input) {
+  std::vector<Node> docs;
+
+  Parser parser(input);
+  while (1) {
+    NodeBuilder builder;
+    if (!parser.HandleNextDocument(builder)) {
+      break;
+    }
+    docs.push_back(builder.Root());
+  }
+
+  return docs;
+}
+
+std::vector<Node> LoadAllFromFile(const std::string& filename) {
+  std::ifstream fin(filename.c_str());
+  if (!fin) {
+    throw BadFile();
+  }
+  return LoadAll(fin);
+}
+}  // namespace YAML