Now config file handles most parameters (but not external potential)

config.h

@@ -0,0 +1,33 @@
+#pragma once
+#include <string>
+#include <unordered_map>
+
+class Config {
+public:
+    Config(std::string file_name);
+
+    double      eps;
+    double      t_end;
+    double      dt_disk;
+    double      dt_contr;
+    double      dt_bh;
+    double      eta;
+    std::string input_file_name;
+    bool        dt_min_warning;
+    int         live_smbh_count;
+    double      live_smbh_custom_eps;
+    bool        live_smbh_output;
+    bool        live_smbh_neighbor_output;
+    int         live_smbh_neighbor_number;
+    bool        binary_smbh_pn;
+    bool        binary_smbh_influence_sphere_output;
+    double      binary_smbh_influence_radius_factor;
+private:
+    using Dictionary = std::unordered_map<std::string,std::string>;
+    Dictionary read_config_file(const std::string file_name);
+    std::string strip(const std::string str);
+    template<typename T> T string_cast(const std::string str);
+    template<typename T> T get_parameter(Dictionary dictionary, std::string name);
+    template<typename T> T get_parameter(Dictionary dictionary, std::string name, T default_value);
+    void error_checking();
+};