add current sensor support to frsky telemetry

this lets the naze emulate the FAS100 current sensor and also transmits
the internally calculated mAh drawn via the fuel level data.

Conflicts:
	src/main/telemetry/frsky.c

Conflicts:
	src/main/telemetry/frsky.c
Make code warnings-free with -pedantic

This removes a function that's no longer used, and inline specifiers
from include file (where they're useless anyway). This makes the whole
default project warnings-free with -Wall -pedantic.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Makefile: link with -nostartfiles

This saves a bit more space and a reasonable thing to do since a
custom startup is used anyway.

Build-tested only.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Makefile: switch to newlib-nano

This makes the binary considerably smaller (73852 text with gcc
4.7.3, 71620 text with gcc 4.9.0 from TNT).

Build-tested only.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>