added M109 file for waiting for temperature when using a fdm printer

I made the M109 Pxxx (xxx being temperature) able to be used when setting the temperature generated from i.e. slic3r or other slicing software.
- bc needs to be installed for computing and comparing the values of current and set temperature
- waiting only works for set temperatures being higher than the current temp. when i.e. you want to wait for the program to wait until the temp is dropped to a certain temperature it doesn't work yet