i2c.c: rename "clock" => "scl" (+ modSsd1306.c). Fixes gh-14

Smoke tested with:

- examples/drivers/BMP180
- examples/drivers/HMC5883L
- examples/drivers/lis3dh
- examples/drivers/mcp23008 (existing and new feature branch)
- examples/drivers/mcp23017 (on new feature branch)

Author: rwaldron

documentation/pins/pins.md

@@ -154,7 +154,7 @@ Pin numbers are device dependent.
 
 The following example instantiates an I2C connection to a [temperature sensor](https://www.sparkfun.com/products/11931) with address 0x48 connected to pins 4 and 5. 
 
-	let sensor = new I2C({sda: 5, clock: 4, address: 0x48});
+	let sensor = new I2C({sda: 5, scl: 4, address: 0x48});
 	sensor.write(0);					// set register address 0
 	let value = sensor.read(2);	// read two bytes
 
@@ -171,15 +171,15 @@ The following example instantiates an I2C connection to a [temperature sensor](h
 
 ### constructor(dictionary)
 
-The I2C constructor takes a dictionary which contains the pins numbers to use for clock and data, as well as the I2C address of the target device.
+The I2C constructor takes a dictionary which contains the pins numbers to use for clock and data (`scl` and `sda` respectively), as well as the I2C address of the target device.
 
-	let sensor = new I2C({sda: 5, clock: 4, address: 0x48});
+	let sensor = new I2C({sda: 5, scl: 4, address: 0x48});
 
 The constructor dictionary has an optional `hz` property to specify the speed of the I2C bus when using this instance.
 
-	let sensor = new I2C({sda: 5, clock: 4, address: 0x48, hz: 1000000});
+	let sensor = new I2C({sda: 5, scl: 4, address: 0x48, hz: 1000000});
 
-Many devices have a default I2C bus. On these devices, the sda and clock parameters may be omitted from the dictionary to use the default I2C bus.
+Many devices have a default I2C bus. On these devices, the `sda` and `scl` parameters may be omitted from the dictionary to use the default I2C bus.
 
 	let sensor = new I2C({address: 0x48});
 

examples/drivers/BMP180/main.js

@@ -119,8 +119,8 @@ class BMP180 extends I2C {
 	}
 }
 
-// SDA = GPIO 4 = D2 - CLOCK = GPIO 5 = D1 - NODEMCU
-let sensor = new BMP180({sda: 4, clock: 5, address: BMP180_ADDR});
+// SDA = GPIO 4 = D2 - SCL = GPIO 5 = D1 - NODEMCU
+let sensor = new BMP180({sda: 4, scl: 5, address: BMP180_ADDR});
 
 WiFi.mode = 2;
 

examples/drivers/HMC5883L/main.js

@@ -18,10 +18,10 @@
 	HMC5883L - https://cdn.sparkfun.com/datasheets/Sensors/Magneto/HMC5883L-FDS.pdf
 */
 
-import SMBus from "smbus";
+import SMBus from "pins/smbus";
 import Timer from "timer";
 
-let sensor = new SMBus({sda: 5, clock: 4, address: 0x1E});
+let sensor = new SMBus({sda: 5, scl: 4, address: 0x1E});
 
 let id = sensor.readBlock(10, 3);			// ID
 id = String.fromCharCode(id[0]) + String.fromCharCode(id[1]) + String.fromCharCode(id[2]);

modules/drivers/ssd1306/modSsd1306.c

@@ -214,7 +214,7 @@ void xs_SSD1306(xsMachine *the)
 	else {
 		xsmcGet(xsVar(0), xsArg(0), xsID_sda);
 		ssd->config.i2c.sda = xsmcToInteger(xsVar(0));
-		xsmcGet(xsVar(0), xsArg(0), xsID_clock);
+		xsmcGet(xsVar(0), xsArg(0), xsID_scl);
 		ssd->config.i2c.scl = xsmcToInteger(xsVar(0));
 
 		ssd->doSPI = 0;

modules/pins/i2c/i2c.c

@@ -41,7 +41,7 @@ void xs_i2c(xsMachine *the)
 	xsmcVars(1);
 	xsmcGet(xsVar(0), xsArg(0), xsID_sda);
 	sda = (xsUndefinedType == xsmcTypeOf(xsVar(0))) ? -1 : xsmcToInteger(xsVar(0));
-	xsmcGet(xsVar(0), xsArg(0), xsID_clock);
+	xsmcGet(xsVar(0), xsArg(0), xsID_scl);
 	scl = (xsUndefinedType == xsmcTypeOf(xsVar(0))) ? -1 : xsmcToInteger(xsVar(0));
 	xsmcGet(xsVar(0), xsArg(0), xsID_address);
 	address = xsmcToInteger(xsVar(0));