CompileMote dialog now keep user make command on changes

[alexrayne]

CompileMote dialog now updates compile make commands script smarter:

• just update begining of make command, with new target
• refreshes NETSTACK_CONF_H macro with new entered netstack header

Fixed refresh of new netstack header on enter it`s name - now it inserts into make commands on enter, or loose editor focus.

[alexrayne]

reworked for more careful make commands update - now only last make command target updates.

also prove macro [CONTIKI_DIR] fr substitute path to contiki from cooja setup. This allow to pass contiki path to make with CONTIKI=[CONTIKI_DIR], and therefore handy build projects, that placed stanalone from contiki repo. You no need to setup path in project`s makefile, but use cooja configured path.