Add a-star based global planner

mg_msgs/action/MoveGlobal.action

@@ -0,0 +1,25 @@
+float64[] x 
+float64[] y 
+
+float64 step 0.01
+float64 tolerance 0.5
+float64 max_wheel_speed 3
+float64 max_angular 3.14
+float64 max_vel 2
+float64 pos_mult 15
+float64 ornt_mult 4
+float64 t_ornt_mult 0.1
+float64 obst_mult_a -5
+float64 obst_mult_b -30
+float64 obst_mult_c -9
+string[] ignore_tags []
+---
+uint8 SUCCESS=0
+uint8 BLOCKED=1
+uint8 TIMEOUT=2
+uint8 MISALIGNED=3
+uint8 UNKNOWN=254
+
+uint8 error
+---
+float64 distance_passed