board/flash: changing flashrom_write signature

	→ changing all flashrom_write() function to the same signature
	→ adding const keyword to signature
dist/pyterm: enable unicode decoding

use unicode streamreader on serial interface
fixes #1371
tests,examples: remove unneeded headers, fix style
pkg/libcoap: fix copmilation problems

Apparently all that whitespace was needed after all.
Next convert to new-style function declrations.
Also, don't prevent make from noticing a failing patch.
tests: add libcoap compilation test
Merge pull request #1347 from SGSSGene/cleanup_signature_fix

unification of flash write signature
Merge pull request #1429 from LudwigOrtmann/libcoap-fixup

pkg/libcoap: fix build AND tests: add one to ensure it does not break in the future
Merge pull request #1381 from LudwigOrtmann/issue-1371

dist/pyterm: enable unicode decoding
Merge pull request #1430 from LudwigOrtmann/test-cleaning

tests,examples: remove unneeded headers, fix style
cpu: atmega_common: Initial import
cpu: atmega2560: Initial import
board: arduino-mega2560: Initial import
tests: blacklist board arduino-mega2560:

    - tests/bloom: value too large for field of 2 bytes
    - tests/<other>: missing headers (time.h or sys/types.h)
test: add download of avr toolchain to .travis.yml
tests: blacklist tests/test_coap and examples that fail due to missing header files
boards: arduino-mega2560: cleanup of Makefiles
boards: arduino-mega2560: cleanup of periph_conf.h: remove left overs from
other board
boards: arduino-mega2560: fix indentation in errno.h
boards: arduino-mega2560: fix LED related defines
boards: arduino-mega2560: clean up LED init