Splitting library into own file. Adding onewire.

The mqtt.c file was getting pretty big, so the example code
is now in main.c. Also, we need a onewire library, so I've
started to write on in onewire.c. We will need to make some
changes to the Makefile as well, but I will need to consult
a couple of resources for that.

Signed-off-by: A.M. Rowsell <amrowsell@frozenelectronics.ca>

onewire.h

@@ -0,0 +1,33 @@
+#include <stdint.h>
+#include "hw_timer.c"
+
+/**
+ * @struct oneWire_t
+ * Structure that holds all the information about onewire connections, including the 64-bit ROM address for each device and some buffer memory to read out the scratchpad
+ */
+typedef struct {
+  uint8_t address[8];
+  uint8_t scratchpad[20];
+} oneWire_t;
+
+/**
+ * @enum ds18b20_cmds
+ * This enum simply gives easy to read names to all the various one-wire commands that the DS18B20 can accept
+ */
+enum ds18b20_cmds {
+  READ_ROM = 0x33,
+  MATCH_ROM = 0x55,
+  SEARCH_ROM = 0xF0,
+  ALARM_SEARCH = 0xEC,
+  SKIP_ROM = 0xCC,
+  CONVERT_T = 0x44,
+  SCRATCH_READ = 0xBE,
+  SCRATCH_WRITE = 0x4E,
+  SCRATCH_COPY = 0x48,
+  E2_RECALL = 0xB8
+};
+
+
+LOCAL void timerISR(void);
+LOCAL void ICACHE_FLASH_ATTR reset(oneWire_t *owDev);
+LOCAL void ICACHE_FLASH_ATTR transact(oneWire_t *owDev, ds18b20_cmds cmd);