Available as Arduino Board Manager entry "Digistump AVR Boards" using the Board Manager URL: https://raw.githubusercontent.com/ArminJo/DigistumpArduino/master/package_digistump_index.json

• To shrink generated code size by 5 to 15 percent (depending on your code) the lto flag was added in platform.txt. To help finding code which consumes the flash, the generating of disassembler and memory map files are added. For Arduino IDE you will find these files in C:\Users<Name>\AppData\Local\Temp\arduino_build_.
• To reflect the smaller bootloader size of micronucleus version 2.5 which allow 6586 instead of 6012 bytes (+11%) the upload.maximum_size entry was changed in boards.txt.
• Since the original gcc version does not support the lto flag, the compiler path was changed to the latest Arduino gcc (7.3.0-atmel3.6.1-arduino5) in the package_digistump_index.json.
• Enabled compiler.cpp.extra_flags.

• Added #define LED_BUILTIN in some pins_arduino.h.
• Added #define __FlashStringHelper fstr_t in Print.h.
• Updated broken extensa links for xtensa-lx106-elf-gcc in package_digistump_index.json.
• Included most pull requests done after the 1.6.7 release like recipe.output.tmp_file={build.project_name}.hex in platform.txt and EEPROM library.
• Added recipe to update booltloader by Arduino IDE.
• Removed the non trusted post_install.bat since Arduino code states: // Set main and bundled indexes as trusted => all others are untrusted.
• Extended DigisparkKeyboard library with 22 keyboard layouts from Teensyduino Core Library, fixed bugs, documented and improved it. Here it is documented how the mapping works, so now you can fix wrong mappings by your own (but please give me feedback to include the fix).

To get all the benefits, just replace the old Digispark board URL http://digistump.com/package_digistump_index.json (e.g. in Arduino File/Preferences) by the new https://raw.githubusercontent.com/ArminJo/DigistumpArduino/master/package_digistump_index.json and install the Digistump AVR Boards version 1.6.8.

For Windows you must install the Digispark driver before you can program the board.
if you have the Diigistump AVR Boards already installed, then the driver is located in %UserProfile%\AppData\Local\Arduino15\packages\digistump\tools\micronucleus\2.0a4. Just execute the Install_Digistump_Drivers.bat file.
Or download it here, open it and run InstallDrivers.exe.

To update your old flash consuming bootloader, open the Arduino IDE, select Tools/Programmer: "Micronucleus" and then run Tools/Burn Bootloder.

The bootloader is the recommended configuration entry_on_power_on_no_pullup_fast_exit_on_no_USB.
Or use one of the window scripts like e.g. Burn_upgrade-t85_default.cmd.
You may also test the t85_agressive bootloader. It works for my boards but the USB timing is not guaranteed as stable as in the other configurations. Do not forget to change the upload.maximum_size entry in %localappdata%\Arduino15\packages\digistump\hardware\avr\1.6.8\boards.txt to 6778.

The Arduino ESP8266 core available with https://arduino.esp8266.com/stable/package_esp8266com_index.json supports the Digistump Oak board now, better use that.

• The original Digistump version with lto and changed upload.maximum_size for micronucleus bootloader 2.5.
• Added LED_BUILTIN definition in pins_arduino.h.
• Added #define __FlashStringHelper fstr_t in tiny/Print.h.
• Updated broken extensa links for xtensa-lx106-elf-gcc in package_digistump_index.json.
• Included most pull requests done after the 1.6.7 release like recipe.output.tmp_file={build.project_name}.hex in platform.txt and EEPROM library.
• Added recipe to update bootloader by Arduino IDE.
• Changed message for BIN redefined in Print.h and it can be suppressed by commenting out #define SUPPRESS_BIN_WARNING in line 39 in Print.h.
• Commented out the annoying #define true 0x1 and #define false 0x0 in wiring.h.
• Removed unnecessary files like .gitignore.
• Added #define TwoWire USI_TWI in Wire.h.
• Changed #include <avr/delay.h> to #include <util/delay.h> in 3 files.
• Included Multi-Keyboard Layout MOD.
• Redefining BIN to 2 for print. BIN can not longer be used as bit position (7) for the x5 ADC "Bipolar Input Mode".
• Enabled all warnings at compile time and removed compiler warnings in tiny core.
• Modified definition for yield() in WProgram.h to avoid error "undefined reference to `yield()'".

Please write me a PM including your motivation/problem if you need a modification or an extension.