set lpc2k_pgm return value

fixes the build not failing when flashing fails
remove cruft from obj dir, add gitignore
add obj/*.d to clean target
Merge pull request #592 from LudwigOrtmann/lpc2k_pgm

Lpc2k pgm
fix calc_rtt

closes #192
Merge pull request #598 from LudwigOrtmann/ping_rtt

fix calc_rtt
update native readme
fix paths in README.md
Merge pull request #600 from LudwigOrtmann/native_readme

update native readme
Merge pull request #599 from LudwigOrtmann/readme_md

fix paths in README.md
remove native cruft from cc110x_ng Makefile
Merge pull request #602 from LudwigOrtmann/cc110x_cruft

remove native cruft from cc110x_ng Makefile
Fix net_help include path
Merge pull request #603 from authmillenon/net_help_include

Fix net_help include path