2.0.1 - ADC Reference fixes, tinyNeoPixel libraries split by port

In pursuit of the goal of eliminating unnecessary tools submenus (which presented problems for sketch maintenance, because submenu settings are not saved with the sketch), the tinyNeoPixel library is no longer a menu option, instead, there are three copies of the library, one for each port - I realize this will break existing sketches (was intended for 2.0.0), but having the sketch require specific submenu options also broke sketches.

Now the only tools submenus are for things that are used to control fuses (which require burn bootloader to set), the clock speed (which in theory is supposed to, but in reality only requires burn bootloader to switch between 16MHz derived clocks and 20MHz derived ones)), and the millis/micros timer, which has to be a submenu because it controls which ISR is defined for millis timekeeping.

Additionally, several bugs relating to the analog references and the DAC introduced by 2.0.0 and 1.1.10 were turned up in testing - this is now fixed. Note also that the EXTERNAL reference option is not present on as many parts as I thought it was - I only know for certain that it's on the "good" 1-series tinies, but existing documentation and header files are unclear about whether it might be present on other chips - so there is also an EXTERNAL_EXPERIMENTAL analogReference() option, available on all parts that don't have , which will try to set the appropriate bits, whether or not the header file says it's there,

Finally, inconsistencies in treatment of the EESAVE fuse for Optiboot boards was fixed - now it is not enabled for these board definitions (previously some had it, and some didn't). Thus, burn bootloader will always clear the EEPROM (and as always, optiboot uploads won't touch the EEPROM - though note that the version of Optiboot included with the core does support EEPROM writes (though the IDE does not have this functionality)

This is the version for board manger installation