cpu: cortexm: fix LTO issue for shared vector table

tests: remove setting TERMFLAGS= before running test

all: fix my email address

Remove setting TERMFLAGS to an empty value as its value will not be set by
`serial.inc.mk` as it is already defined.

tests: added some more pexpect scripts

lostandfound: fix some typos / wording

make: tools: serial: allow for using picocom as term prog

openocd: Refactor openocd.sh script

cpu, cc2538: fix pm, don't go into  cortexm_sleep(0)

    fixes #7746

board/calliope: fix board calliope rev1

Fixes problems with the watchdog interfering on Kinetis K devices
when USE_OLD_OPENOCD=0.

- Merge flash and flash-elf commands since they were identical except
  for the file name of the image
- Split GDB command from DBG environment variable to allow more easily
  configure front-ends for GDB via environment variables.
- Remove verbose tests of empty variables and replace by `: ${VAR:=default}`
- Remove passed command line arguments to sub-functions, they were
  unused in the functions anyway.
- Remove TUI variable, use `export DBG_EXTRA_FLAGS=-tui` to get the same
  result.

linux_can: fix library dependency

Exporting the `LINKFLAGS` messes with the buildtest environment
somehow.

It is however not required to export them here (as a still successful
build of `tests/conn_can` on native proves)

murdock: fail on broken application Makefile

tests: fixed INSUF_MEM define for gnrc_ipv6_nib_6ln

boards/z1: fixed LEDx_PIN definitions

pm: fix pm fallback selection

Instead of using `weak` function definitions, this PR handles
default implementations using `PROVIDES_x` defines, allowing
for cpus/pm realted modules to use their own implementations.

cpu/stm32_common: fix stm32f1/2/4 pm