Release 0.1.24 - Improved variable detection in else/elif, start of def statement implementation

Overview

Main focus of this release is fixing detection of variables inside
else/elif statements and internal changes.

These fixes actually enable some fun things - like the ability to control
complex robots - like robot puppies/kittens with multi-motor limbs and
sensors, so an example of doing that has been added. It's probably
the first major non-trivial example.

Additionally the ability to extend the arduino profile has been made
easier through bundling together everything to do with the arduino
profile into pyxie/profile/arduino.py . This also acts a template for
creation of other profiles. (For example, I'll add a micro:bit profile
at some point) See the changelog for more details.

There's been a number of other changes. Some internal which aren't really
user facing, but affect development - such as major reprioritisation
of the backlog (see www.sparkslabs.com/pyxie/dev-status.html). The
pyxie-dev tool I use for managing releases has been overhauled. There's
been significant improvements to the way pynodes are handled as well.

Lastly, I don't normally talk about upcoming changes, but I've started
the beginnings of implementation of user functions - ie def statements.
The python parsing side and analysis side has been completed for
functions with no arguments, no return values, and so on. However,
the conversion of this to the C++ side of things really requires
major changes to the internals of how the C++ is generated.

This will take time, so this release just contains the parsing,
and analysis side of things. The next release should contain code
generation and compilation.

Changelog

What's been fixed?

• Code generation for else/elif was failing when the statements inside
  contained identifiers. This was due to context not propogating into
  else/elif. This was caused by neither if nor elif adding else clauses
  as children. This was done and now this operates correctly.

What's New?

• Added playful puppy example that compiles and controls the Dagu Playful Puppy
  robot. (8 leg servos, 2 head/neck servos, infrared array sensor/eye)
  • v0 no funcs Playful Puppy code analyses #213
  • v0 no funcs Playful Puppy code generates code #214
  • v0 no funcs Playful Puppy code compiles, & runs on device correctly #215
• Profile specific code has been extracted to a specific file. In this
  case, the iniitial profile made more managable is of course the arduino
  profile. To configure this/extend this, you now update the file
  pyxie/profile/arduino.py
• To add more predefined variables/etc that are used in the context (ala
  A0, etc) you extend the function populate_profile_context.
• If you need to add extra types - ala the Servo type - you can use
  the Servo function call as an example. Note that it has a return
  type of Servo. This means of course that the Servo function is
  a constructor. For this to work clearly the type needs to be
  defined - so you define it below in the variable types.
• Started on parsing side aspects of definition of simple user functions.
  (ie def statements) Hopefully basic functions should be in the next
  iteration of pyxie.

Internal Changes

• pyxie-dev - Pyxie's release management tool, has had an overhaul,
  and transferred into the pyxie package, rather than standalone code.
  In the process code was improved, such that "dryrun" and "verbose"
  now mean precisely that. Help text is deliberately verbose to note
  what the release process is.
• Check all Pynodes add all sub nodes as children correctly #264
• Start of function support:
  • Lexing for function definition succeeds #265
  • Grammar parsing for function definition succeeds #266
  • Pynode support for def statements #269.
  • Add a callable type #270

Other

• Reorganised backlog based on priorities - need, useful, want, wouldlike.
  Plan going forward is to primarily focus on needs, and one or two from
  each of the other categories.
• Function call code supports simplified type definitions for externals. #34
• Block structure of generated C Code is pretty/human friendly/readable #26
• Add special case for function calls like print #37