Fix a few compile errors against avr-gcc 4.7 on ubuntu.

"variable ‘helpText1’ must be const in order to be put into read-only section by means of ‘__attribute__((progmem))’"

Author: Jasper Klein

PortsSHT11.cpp

@@ -21,7 +21,7 @@ enum {
     RESET        = 0x1e,
 };
 
-static uint8_t crcTab [] PROGMEM = {
+const static uint8_t crcTab [] PROGMEM = {
     0, 49, 98, 83, 196, 245, 166, 151, 185, 136, 219, 234, 125, 76, 31, 46, 67,
     114, 33, 16, 135, 182, 229, 212, 250, 203, 152, 169, 62, 15, 92, 109, 134,
     183, 228, 213, 66, 115, 32, 17, 63, 14, 93, 108, 251, 202, 153, 168, 197,

examples/RF12/RF12demo/RF12demo.ino

@@ -526,7 +526,7 @@ static void df_replay (word seqnum, long asof) {
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-char helpText1[] PROGMEM = 
+const char helpText1[] PROGMEM = 
     "\n"
     "Available commands:" "\n"
     "  <nn> i     - set node ID (standard node ids are 1..26)" "\n"
@@ -543,7 +543,7 @@ char helpText1[] PROGMEM =
     "  <hchi>,<hclo>,<addr>,<cmd> f     - FS20 command (868 MHz)" "\n"
     "  <addr>,<dev>,<on> k              - KAKU command (433 MHz)" "\n"
 ;
-char helpText2[] PROGMEM = 
+const char helpText2[] PROGMEM = 
     "Flash storage (JeeLink only):" "\n"
     "  d                                - dump all log markers" "\n"
     "  <sh>,<sl>,<t3>,<t2>,<t1>,<t0> r  - replay from specified marker" "\n"