v0.29: Various bugfixes, SConstruct custom builds

This release fixes quite a few bugs, further stabilizing the APIs and the extension.

• It's now possible to build custom programs using SConstruct
  • When a SCons file is present, saving a .cpp file will invoke scons instead
• Make it possible to disable execution timeout by setting it to 0, which yields up to 13% performance
  • If the sandbox program loops forever the game can still be closed from the editor or process explorer, like other hung processes
• Completely disable all socket calls, reducing size of all shipped binaries
• Add a work-around for an issue with icon registration in the Android editor
• Fix mishap with BCLR and BINV instruction bitmasks, leading to exception about unimplemented opcodes
• Fix PackedVector3Array not able to be constructed from a Variant
• Fix Sandbox monitoring properties being inadvertently stored in project file
• Many improvements made to Array and PackedArray<> interactions
• Improve support for double builds, add DOUBLE_PRECISION CMake option to enable in custom builds
• Add size() and is_empty() to packed arrays
• Add support for PackedVector4Array
• Add a new Sandbox property that limits maximum heap allocations
• Add monitoring that shows arena allocations, deallocations and current chunk usage
• Add EXPECT() macro to the API
• Increase the argument limit for vmcallv to 16 (unxboxing disabled)
• Increase the argument limit for vmcall to up to 11 arguments (unboxing enabled)
  • The limit is still 7 integral and 8 fp arguments, but can now be better spread out

PRs

• Update SCsub for linux by @Ughuuu in #208
• Fix windows target for module build 1/2 by @Ughuuu in #211
• Build using SConstruct, when present by @Ughuuu in #213

Full Changelog: v0.28...v0.29