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/regex_yaml.cpp

@@ -0,0 +1,45 @@
+#include "regex_yaml.h"
+
+namespace YAML {
+// constructors
+RegEx::RegEx() : m_op(REGEX_EMPTY) {}
+
+RegEx::RegEx(REGEX_OP op) : m_op(op) {}
+
+RegEx::RegEx(char ch) : m_op(REGEX_MATCH), m_a(ch) {}
+
+RegEx::RegEx(char a, char z) : m_op(REGEX_RANGE), m_a(a), m_z(z) {}
+
+RegEx::RegEx(const std::string& str, REGEX_OP op) : m_op(op) {
+  for (std::size_t i = 0; i < str.size(); i++)
+    m_params.push_back(RegEx(str[i]));
+}
+
+// combination constructors
+RegEx operator!(const RegEx& ex) {
+  RegEx ret(REGEX_NOT);
+  ret.m_params.push_back(ex);
+  return ret;
+}
+
+RegEx operator||(const RegEx& ex1, const RegEx& ex2) {
+  RegEx ret(REGEX_OR);
+  ret.m_params.push_back(ex1);
+  ret.m_params.push_back(ex2);
+  return ret;
+}
+
+RegEx operator&&(const RegEx& ex1, const RegEx& ex2) {
+  RegEx ret(REGEX_AND);
+  ret.m_params.push_back(ex1);
+  ret.m_params.push_back(ex2);
+  return ret;
+}
+
+RegEx operator+(const RegEx& ex1, const RegEx& ex2) {
+  RegEx ret(REGEX_SEQ);
+  ret.m_params.push_back(ex1);
+  ret.m_params.push_back(ex2);
+  return ret;
+}
+}