Improve sample applications

[mikee47]

This PR updates all the main Sming samples to try and demonstrate best practice when coding Sming applications. Specifically:

• Initialise timers using templated methods where possible as this provides static range check on values
• Using SimpleTimer is sufficient in most cases. This is both more efficient and avoids complication where compiler cannot distinguish between delegates and callback functions.
• Use timer startOnce() method rather than start(false)
• Use C++ iterators in preference to C-style loops for(int i=0; i<list.count(); ++i) {...}
• Ensure consistent use of WIFI_SSID and WIFI_PASSWORD
• Use Serial methods in preference to debug_x where intent is not actually for debugging
• Use anonymous namespaces and remove redundant static declarations
• Avoid nested if statements
• Place init() function at end of main application source file
• Reduce variable scope (declare at point of first use)
• static/global variables do not require explicit initialisation to 0

Sample-specific changes:

• Revise HttpServer_AJAX so that GPIO numbers are consistent with web code
• Update Basic_Ssl keys, requires Bearssl
• Update Basic_DateTime sample
  • Simplify code using LineBuffer
  • Accept either numeric timestamp or HTTP date string. Note: ISO8601 string conversion not currently supported by DateTime.
  • Don't emulate console via telnet, use default CLI
• Rewrite Basic_Neopixel sample
  • Enumerate color values
  • Reduce global variables and duplicated code
  • Verify logic flow using Host
• Rewrite Display_TM1637 as state machine (coroutine)
• Fix Basic_Storage, didn't actually use RAM as indicated
• Add Host Print stream support, update Basic_Utility sample

Other changes

• Update jerryscript library to latest. CI improvements and removes deprecation warnings.
• Fix bad memory casts in si4432 library. Also builds for other architectures than esp8266, so remove SOC restrictions.
• Fix unused variable warning in CommandProcessing library

[slaff]

Awesome work @mikee47 ! I will be more active next week and start reviewing the other PRs. Please, be patient with me as I am away from a proper computer at the moment :)

[mikee47]

@slaff No worries, we all have lives to lead!