Don't change build systems automatically
Remove automatic build sys selection for pubspec
Add helpers for managing our own build system
Implement custom build system infrastructure

- We no longer use the default build system framework as the
  primary framework for building files in dart projects.
- Create a notion of a 'primary' and 'secondary' actions, mapped
  to F7 and Ctrl+F7 by default.
- Add smarter context detection so that the new build system knows
  how it should build the files.

Advantages:
- Eliminates conflicts with non-Dart build systems.
- More flexibility to perform sensible build operations.

Disadvantages:
- Temporary loss of convenience. Some features present in the
  default build systems have not been ported yet.
Fix bug; refactor
Add regexes
Merge pull request #221 from my-personal-forks/build

Replacement build system for Dart projects
Fix error
Prepare release
Merge pull request #222 from my-personal-forks/prepare-release

Prepare release
Modify 'exec' command so we have more control over it

The new command accepts a 'preamble' argument to print a
preamble as early feedback for users.
Refactor build commands
Refactor
Merge pull request #224 from my-personal-forks/refactor-build

Refactor new build system
Fix typo
Merge pull request #226 from my-personal-forks/refactor-build

Fix typo
Add setting to locate Dartium
Restrict 'launch' key bindings to 'dart_can_do_launch' context
Add third party lib
Add non-fatal ConfigError class