py/mpprint: Fix int formatting so "+" is printed for 0-valued integer.
py/mpprint: Fix int formatting so "+" is printed for 0-valued integer.

pfalcon/micropython,cwyark/micropython,tobbad/micropython,alex-robbins/micropython,ryannathans/micropython,kerneltask/micropython,pramasoul/micropython,deshipu/micropython,HenrikSolver/micropython,blazewicz/micropython,trezor/micropython,kerneltask/micropython,tralamazza/micropython,henriknelson/micropython,SHA2017-badge/micropython-esp32,oopy/micropython,pramasoul/micropython,SHA2017-badge/micropython-esp32,HenrikSolver/micropython,TDAbboud/micropython,torwag/micropython,selste/micropython,adafruit/micropython,micropython/micropython-esp32,pfalcon/micropython,toolmacher/micropython,lowRISC/micropython,swegener/micropython,toolmacher/micropython,tobbad/micropython,hiway/micropython,hiway/micropython,lowRISC/micropython,pramasoul/micropython,adafruit/circuitpython,tralamazza/micropython,blazewicz/micropython,MrSurly/micropython-esp32,pozetroninc/micropython,cwyark/micropython,PappaPeppar/micropython,pfalcon/micropython,AriZuu/micropython,hiway/micropython,alex-robbins/micropython,oopy/micropython,tralamazza/micropython,AriZuu/micropython,selste/micropython,lowRISC/micropython,MrSurly/micropython,pfalcon/micropython,puuu/micropython,adafruit/circuitpython,bvernoux/micropython,trezor/micropython,SHA2017-badge/micropython-esp32,bvernoux/micropython,deshipu/micropython,infinnovation/micropython,toolmacher/micropython,swegener/micropython,AriZuu/micropython,puuu/micropython,henriknelson/micropython,alex-robbins/micropython,MrSurly/micropython-esp32,adafruit/micropython,adafruit/micropython,kerneltask/micropython,PappaPeppar/micropython,TDAbboud/micropython,Peetz0r/micropython-esp32,Timmenem/micropython,chrisdearman/micropython,swegener/micropython,PappaPeppar/micropython,blazewicz/micropython,swegener/micropython,selste/micropython,micropython/micropython-esp32,hiway/micropython,MrSurly/micropython,pozetroninc/micropython,SHA2017-badge/micropython-esp32,alex-robbins/micropython,HenrikSolver/micropython,SHA2017-badge/micropython-esp32,ryannathans/micropython,bvernoux/micropython,selste/micropython,puuu/micropython,blazewicz/micropython,TDAbboud/micropython,MrSurly/micropython-esp32,adafruit/micropython,Timmenem/micropython,hiway/micropython,torwag/micropython,infinnovation/micropython,adafruit/circuitpython,torwag/micropython,Peetz0r/micropython-esp32,micropython/micropython-esp32,micropython/micropython-esp32,tralamazza/micropython,trezor/micropython,pramasoul/micropython,toolmacher/micropython,cwyark/micropython,TDAbboud/micropython,henriknelson/micropython,Peetz0r/micropython-esp32,infinnovation/micropython,dmazzella/micropython,adafruit/circuitpython,dmazzella/micropython,blazewicz/micropython,tobbad/micropython,lowRISC/micropython,HenrikSolver/micropython,dmazzella/micropython,pozetroninc/micropython,MrSurly/micropython-esp32,MrSurly/micropython,tobbad/micropython,oopy/micropython,toolmacher/micropython,ryannathans/micropython,adafruit/circuitpython,Timmenem/micropython,adafruit/circuitpython,chrisdearman/micropython,infinnovation/micropython,deshipu/micropython,Peetz0r/micropython-esp32,alex-robbins/micropython,lowRISC/micropython,oopy/micropython,pfalcon/micropython,ryannathans/micropython,pozetroninc/micropython,adafruit/micropython,MrSurly/micropython,AriZuu/micropython,cwyark/micropython,oopy/micropython,chrisdearman/micropython,TDAbboud/micropython,cwyark/micropython,selste/micropython,swegener/micropython,pozetroninc/micropython,deshipu/micropython,deshipu/micropython,trezor/micropython,bvernoux/micropython,kerneltask/micropython,henriknelson/micropython,MrSurly/micropython,torwag/micropython,henriknelson/micropython,PappaPeppar/micropython,pramasoul/micropython,chrisdearman/micropython,Peetz0r/micropython-esp32,kerneltask/micropython,bvernoux/micropython,tobbad/micropython,puuu/micropython,Timmenem/micropython,torwag/micropython,chrisdearman/micropython,infinnovation/micropython,MrSurly/micropython-esp32,puuu/micropython,trezor/micropython,micropython/micropython-esp32,ryannathans/micropython,dmazzella/micropython,Timmenem/micropython,HenrikSolver/micropython,PappaPeppar/micropython,AriZuu/micropython