nsh env variables expanding
Revert "nsh env variables expanding"

This reverts commit cb7f30317a655f620dfc905069c9066494e99161.
nsh: env variables expansion
nsh: don’t try to expand env variables in nsh_argument
nsh: fixed syntax checking in env variables expanding
nsh: code style fixed
Assembler changes with the gcc-47 distribution from ARM mean that we need to be explicit about branch sizes; one or more of the wide branch opcodes results in bad table branching.
typo, wide branch should be narrow
stm32_serial: fixed spelling of FLOWCONTROL config option in stm32 serial code

this fixes flow control on pixhawk
FAT: move cluster expansion checks to start of IO loops

this fixes a filesystem corruption bug at cluster boundaries. Thanks
to tkloss for reporting the issue.

Fixes issue #12