add support for Raspberry Pico

/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp: In function 'void handle_interrupts(timer16_Sequence_t, volatile uint16_t*, volatile uint16_t*)':
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:148:16: warning: conversion from 'unsigned int' to 'uint16_t' {aka 'short unsigned int'} changes value from '332500' to '4820' [-Woverflow]
  148 |       *OCRnA = (unsigned int)usToTicks(REFRESH_INTERVAL);
      |                ^
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp: At global scope:
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:158:8: error: expected constructor, destructor, or type conversion before '(' token
  158 | SIGNAL (TIMER1_COMPA_vect)
      |        ^
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp: In function 'void initISR(timer16_Sequence_t)':
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:206:5: error: 'TCCR1A' was not declared in this scope
  206 |     TCCR1A = 0;             // normal counting mode
      |     ^~~~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:207:5: error: 'TCCR1B' was not declared in this scope
  207 |     TCCR1B = _BV(CS11);     // set prescaler of 8
      |     ^~~~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:207:18: error: 'CS11' was not declared in this scope
  207 |     TCCR1B = _BV(CS11);     // set prescaler of 8
      |                  ^~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:207:14: error: '_BV' was not declared in this scope
  207 |     TCCR1B = _BV(CS11);     // set prescaler of 8
      |              ^~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:208:5: error: 'TCNT1' was not declared in this scope
  208 |     TCNT1 = 0;              // clear the timer count
      |     ^~~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:214:5: error: 'TIFR1' was not declared in this scope
  214 |     TIFR1 |= _BV(OCF1A);     // clear any pending interrupts;
      |     ^~~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:214:18: error: 'OCF1A' was not declared in this scope
  214 |     TIFR1 |= _BV(OCF1A);     // clear any pending interrupts;
      |                  ^~~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:215:5: error: 'TIMSK1' was not declared in this scope
  215 |     TIMSK1 |=  _BV(OCIE1A) ; // enable the output compare interrupt
      |     ^~~~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:215:20: error: 'OCIE1A' was not declared in this scope
  215 |     TIMSK1 |=  _BV(OCIE1A) ; // enable the output compare interrupt
      |                    ^~~~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp: In member function 'void VarSpeedServo::writeMicroseconds(int)':
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:374:23: error: 'SREG' was not declared in this scope
  374 |     uint8_t oldSREG = SREG;
      |                       ^~~~
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp: In member function 'void VarSpeedServo::write(int, uint8_t)':
/root/Arduino/libraries/VarSpeedServo/VarSpeedServo.cpp:422:22: error: 'SREG' was not declared in this scope
  422 |    uint8_t oldSREG = SREG;
      |                      ^~~~

Using library VarSpeedServo in folder: /root/Arduino/libraries/VarSpeedServo (legacy)
Using library Wire at version 1.0 in folder: /root/.arduino15/packages/rp2040/hardware/rp2040/3.1.1/libraries/Wire
Using library MPU6050 at version 0.6.0 in folder: /root/Arduino/libraries/MPU6050
netlabtoolkit / VarSpeedServo

add support for Raspberry Pico #47
