fix compile warnings + make work with busio library!

Author: ladyada

libraries/Wire/TinyWireM.cpp

@@ -59,7 +59,7 @@ size_t TinyM_USI_TWI::write(uint8_t data){ // buffers up data to send
 }
 
 uint8_t TinyM_USI_TWI::endTransmission() {
-  endTransmission(1);
+  return endTransmission(1);
 }
 
 uint8_t TinyM_USI_TWI::endTransmission(uint8_t stop){ // actually sends the buffer

libraries/Wire/TinyWireM.h

@@ -83,6 +83,8 @@ class TinyM_USI_TWI
 
 extern TinyM_USI_TWI Wire;
 
+typedef TinyM_USI_TWI TwoWire;
+
 #endif
 
 #endif //attiny85

variants/tiny8/pins_arduino.h

@@ -47,6 +47,7 @@
 #define NUM_DIGITAL_PINS            3
 #define NUM_ANALOG_INPUTS           1
 #define LED_BUILTIN 1
+#define SPI_INTERFACES_COUNT 0
 
 #define PIN_A0               (6)
 #define PIN_A1               (7)