Sensor Watch Simulator (#35)

* Put something on screen

* Use the 32bit watch_date_time repr to pass from JS

* Implement periodic callbacks

* Clear display on enabling

* Hook up watch_set_led_color() to SVG (green-only)

* Make debug output full-width

* Remove default Emscripten canvas

* Implement sleep and button clicks

* Fix time zone conversion bug in beats-time app

* Clean up warnings

* Fix pin levels

* Set time zone to browser value (if available)

* Add basic backup data saving

* Silence format specifier warnings in both targets

* Remove unnecessary, copied files

* Use RTC pointer to clear callbacks (if available)

* Use preprocessor define to avoid hardcoding MOVEMENT_NUM_FACES

* Change each face to const preprocessor definition

* Remove Intl.DateTimeFormat usage

* Update shell.html title, header

* Add touch start/end event handlers on SVG buttons

* Update shell.html

* Update folder structure (shared, simulator, hardware under watch-library)

* Tease out shared components from watch_slcd

* Clean up simulator watch_slcd.c inline JS calls

* Fix missing newlines at end of file

* Add simulator warnings (except format, unused-paremter)

* Implement remaining watch_rtc functions

* Fix button bug on mouse down then drag out

* Implement remaining watch_slcd functions

* Link keyboard events to buttons (for keys A, L, M)

* Rewrite event handling (mouse, touch, keyboard) in C

* Set explicit text UTF-8 charset in shell.html

* Address PR comments

* Remove unused directories from include paths

watch-library/hardware/hal/documentation/flash.rst

@@ -0,0 +1,52 @@
+The Flash Driver
+================
+
+Flash is a re-programmable memory that retains program and data
+storage even with power off.
+
+User can write or read several bytes from any valid address in a flash.
+
+As to the erase/lock/unlock command, the input parameter of address should
+be a bytes address aligned with the page start, otherwise, the command will fail
+to be executed. At the meantime, the number of pages that can be locked or unlocked
+at once depends on region size of the flash. User can get the real number
+from the function return value which could be different for the different devices.
+
+Features
+--------
+
+* Initialization/de-initialization
+* Writing/Reading bytes
+* Locking/Unlocking/Erasing pages
+* Notifications about errors or being ready for a new command
+
+Applications
+------------
+
+* Mini disk which can retain program and data storage
+* Boot loader
+* Non volatile storage
+
+Dependencies
+------------
+
+The peripheral which controls a re-programmable flash memory.
+
+Concurrency
+-----------
+
+N/A
+
+Limitations
+-----------
+
+User should pay attention to set a proper stack size in their application,
+since the driver manages a temporary buffer in stack to cache unchanged data
+when calling flash write and erase function.
+Due to flash memory architecture of SAMD21/D20/L21/L22/C20/C21/D09/D10/D11/R21,
+write operation erazes row content before each write.
+
+Known issues and workarounds
+----------------------------
+
+N/A