Merge branch 'master' into skytraq

diff --cc skytraq.cc
index 913262a312d2759582b2ddfada74b4df68d148e6,0f7e75232e55715eb8d96c5289c3306604f25bf1..a7e869b45a266df7d85627ec21c41b82370627ed
--- 1/skytraq.cc
--- 2/skytraq.cc
+++ b/skytraq.cc
@@@ -269,11 -289,11 +289,11 @@@ skytraq_calc_checksum(const unsigned ch
  }
  
  static int
- skytraq_rd_msg(const void* payload, unsigned int len)
+ skytraq_rd_msg(void* payload, unsigned int len)
  {
 -  int errors = 5;             /* allow this many errors */
 +  int errors = 5;             // Allow this many receiver errors silently.
    unsigned int c, i, state;
 -  int rcv_len;
 +  signed int rcv_len;         // Negative length is read error.
  
    for (i = 0, state = 0; i < RETRIES && state < sizeof(MSG_START); i++) {
      c = rd_char(&errors);