py: Fix typing of viper locals; allow default types in annotation.
py: Viper can now store to global.
modified:  teensy/README.md

Updated teensy/README.md to reflect change in build process (teensyduino is no
longer required for build).
teensy/README.md (corrected typo)
Merge branch 'danpeirce-master'
stmhal: For non-debug compile, enable CC/LD opt to remove dead code.

Saves over 35k ROM due to elimination of unused HAL functions.  All
tests pass.

Addresses issue #702.
tests: Wait for just over 1 sec when testing RTC.

Waiting for 1000ms between seconds of RTC is sometimes too quick.
Waiting for 1001ms is enough for the RTC to pass 1 second.
stmhal: Fix printing of pin name in error message.
stmhal: In safe mode, still mount SD card and present as MSD over USB.

It's still "safe" because no scripts are run.  Remove the SD card if you
want to access the internal flash filesystem.  Addresses issue #616.

Also: remove obsolete pyb.source_dir setting, and reset pyb.main and
pyb.usb_mode settings on soft-reset.
py: Put SystemExit in builtin namespace.

Also fix unix port so that SystemExit with no arg exits with value 0.
Put some code into the first 16K of flash

This basically shrinks the remaining size of flash in the portion
that goes after the internal flash drive.
Merge pull request #803 from dhylands/ld-opt

Put some code into the first 16K of flash
Working on timer-pwm