This includes empty stubs for most core Arduino functions.
Need to actually implement all those digital reads writes whatever.
Need to prebuild toolchains (xtensa-elf-lx106) for 3 platforms and put them on some download server.
Need to do the same with esptool.
Need to fix 0x40000 binary generation and add correct upload commands.
Maybe even implement uploads over WiFi.
An exported UTI declaration means that the type is available for use by all other parties.
By adding an this declaration for ino files, it allows Quick Look to display file content and
external editors (like Xcode) to automatically syntax highlight .ino files as C++
Before, core.a would be rebuilt on every build, even when none of the
core .o files changed. Now, the timestamps are checked against the
timestamp on core.a first, skipping the build if nothing changed.
Because this uses the current list of .o files, there is a corner case
when a source file is deleted, but no other source file is modified. In
that case, core.a is not rebuilt, even though it should be. However,
this is such a narrow and unrealistic case, that it should pose a real
problem.
This fixes part of #1991
This prevents a half-finished core.a file from lingering around.
Currently, this should not make a difference since core.a is rebuilt
every time, but this prepares for skipping this build step if possible.
Before, the ar command was just ran for all .o files that should end up
in core.a, which should replace any old code in core.a. However, it
seems that in the unlikely event that functions or entire source files
are deleted, they might linger in the core.a file.
