Stack sweep

This PR fixes the stack sizes for a number of modules. The sizes in the modules.mk are only the command line tool stacks and were excessively large, contributing to memory fragmentation during boot. Also shaved slightly off the commander and mavlink application stacks.

Free with 2 MAVLink instances on multicopter and with BlinkM loaded:

```
nsh> free
             total       used       free    largest
Mem:        177456     167040      10416       2624
```

And processes:

```
Processes: 21 total, 3 running, 18 sleeping
CPU usage: 48.26% tasks, 0.59% sched, 51.15% idle
Uptime: 53.711s total, 27.202s idle

 PID COMMAND                   CPU(ms) CPU(%)  USED/STACK PRIO(BASE) STATE 
   0 Idle Task                   27206 51.150     0/    0   0 (  0)  READY 
   1 hpwork                       1885  3.489   740/ 2040 192 (192)  w:sig 
   2 lpwork                        300  0.519  1156/ 2040  50 ( 50)  READY 
   3 init                          429  0.000  1420/ 4088 100 (100)  w:sem 
 122 top                           134  4.454  1220/ 2040 100 (100)  RUN   
  52 commander                     221  0.222  1996/ 2792 215 (215)  w:sig 
  53 commander_low_prio             17  0.000   604/ 2984  50 ( 50)  w:sem 
  55 px4io                        2349  4.528   916/ 2040 240 (240)  w:sem 
  60 mavlink_if0                   590  1.113  1028/ 1792 100 (100)  w:sig 
  61 mavlink_rcv_if0                25  0.000   788/ 2992 215 (215)  w:sem 
  76 sensors_task                 1903  3.860   876/ 2040 250 (250)  w:sem 
 102 position_estimator_inav      1423  2.746  2388/ 4088 250 (250)  w:sem 
  80 sdlog2                        250  0.148  1852/ 2992  70 ( 70)  w:sig 
  83 gps                           195  0.371   972/ 2040 220 (220)  w:sem 
 100 attitude_estimator_ekf      11272 21.603 12916/13992 250 (250)  w:sem 
 104 mc_att_control               1998  3.860  1100/ 2040 250 (250)  w:sem 
 106 mc_pos_control                394  0.816  1028/ 2040 250 (250)  w:sem 
 110 dataman                       701  0.000   692/ 2040 250 (250)  w:sem 
 120 mavlink_if1                  2053  0.000  1124/ 1792 215 (100)  w:sem 
 113 navigator                     256  0.519   868/ 2040 250 (250)  w:sem 
 121 mavlink_rcv_if1                 4  0.000  1268/ 2992 215 (215)  w:sem 
```