Addressed much larger flash size with avr-gcc v4.9.2. Refactored reports to save 160KB.

- The newest Arduino IDE 1.6.12 has recently updated to avr-gcc v4.9.2.
Unfortunately, it produces a compiled size almost 0.7KB to 1KB larger
than prior versions! This can easily cause the base build to exceed the
Arduino Duemilanove/Nano flash limit of 30.5KB. The Arduino Uno seems
to be ok still with its 31.5KB flash limit.

- Makefile `-flto` compile flag added to cut down on the horrible flash
size when using the new avr-gcc. (Edit Makefile and remove comment on
COMPILE definition). This brings it in-line with what the IDE produces.

- Functionalized repetitive tasks in report.c to try to reduce overall
flash size. Successfully cut down about 160bytes.

- Removed printFloat_SettingValue() and printFloat_RPMValue()
functions. These aren’t required and can be replaced with a direct call
to printFloat() because they don’t require a unit conversion check.

grbl/print.c

@@ -173,7 +173,6 @@ void printFloat(float n, uint8_t decimal_places)
 // in the config.h.
 //  - CoordValue: Handles all position or coordinate values in inches or mm reporting.
 //  - RateValue: Handles feed rate and current velocity in inches or mm reporting.
-//  - SettingValue: Handles all floating point settings values (always in mm.)
 void printFloat_CoordValue(float n) {
   if (bit_istrue(settings.flags,BITFLAG_REPORT_INCHES)) {
     printFloat(n*INCH_PER_MM,N_DECIMAL_COORDVALUE_INCH);
@@ -190,10 +189,6 @@ void printFloat_RateValue(float n) {
   }
 }
 
-// void printFloat_SettingValue(float n) { printFloat(n,N_DECIMAL_SETTINGVALUE); }
-
-void printFloat_RPMValue(float n) { printFloat(n,N_DECIMAL_RPMVALUE); }
-
 // Debug tool to print free memory in bytes at the called point.
 // NOTE: Keep commented unless using. Part of this function always gets compiled in.
 // void printFreeMemory()