Make some settings configurable

[gropi75]

Following variables are currenty fixed in the code. They should be removed from secrets.h and made adjustable over the Settings tab of the GUI.
At the same time they should be stored in the permanent storage of the SEM32 controller.

char mqtt_server[40]
char mqtt_port[6]
char current_clamp_ip[40]
char current_clamp_cmd[40]
char sensor_resp[20]
char sensor_resp_power[20]
char solarprognose_token[40] = "token"; // token to get prognosis from http://www.solarprognose.de
char solarprognose_id[4] = "999";
float lagmorning=0; // time in decimal hours between real sunset and start of PV
float lagevening=0; // time in decimal hours between end of PV power production and real sunset
float laenge // Postition of PV
float breite // Position of PV