_writeResolution, set by analogWriteResolution(), is shared by the DAC and PWM

[tedtoal]

The resolution value _writeResolution, set by analogWriteResolution(), is shared by the DAC and PWM. There is no reason why this needs to be so.

I recommend the following changes to fix this:

28c31,32
< static int _writeResolution = 8;
---
> static int _writeResolution_DAC = 8;
> static int _writeResolution_PWM = 8;
74c78,89
<   _writeResolution = res;
---
>   _writeResolution_DAC = res;
>   _writeResolution_PWM = res;
> }
> 
> void analogWriteResolution_DAC(int res)
> {
>   _writeResolution_DAC = res;
> }
> 
> void analogWriteResolution_PWM(int res)
> {
>   _writeResolution_PWM = res;
207c240
<     value = mapResolution(value, _writeResolution, 10);
---
>     value = mapResolution(value, _writeResolution_DAC, 10);
219c252
<     value = mapResolution(value, _writeResolution, 16);
---
>     value = mapResolution(value, _writeResolution_PWM, 16);