What was the error, when you wanted to compile? Are these line exists in esp32.h:
#define SDA_PIN 5
#define SCL_PIN 4
?
Wire.begin should look like this: Wire.begin(SDA_PIN, SCL_PIN);
Sorry, forgot one thing. Please modify I2CRTC.cpp also! Line 46. You also have to remove the comment block signs ‘/*’ and ‘*/’ from the begining (line 32 and 37), so esp32.h gets included.
(search for SDA in the whole Opensprinkler.cpp)