When CFLAGS_EXTRA/LDFLAGS_EXTRA (or anything) is set on the command line of
a make invocation then it will completely override any setting or appending
of these variables in the makefile(s). This means builds like the coverage
variant will have their mpconfigvariant.mk settings overridden. Fix this
by using CFLAGS/LDFLAGS exclusively in the makefile(s), reserving the
CFLAGS_EXTRA/LDFLAGS_EXTRA variables for external command-line use only.
This commit adds backward-word, backward-kill-word, forward-word,
forward-kill-word sequences for the REPL, with bindings to Alt+F, Alt+B,
Alt+D and Alt+Backspace respectively. It is disabled by default and can be
enabled via MICROPY_REPL_EMACS_WORDS_MOVE.
Further enabling MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE adds extra bindings
for these new sequences: Ctrl+Right, Ctrl+Left and Ctrl+W.
The features are enabled on unix micropython-coverage and micropython-dev.
Invoking "make" will still build the standard "micropython" executable, but
other variants are now build using, eg, "make VARIANT=minimal". This
follows how bare-metal ports specify a particular board, and allows running
any make target (eg clean, test) with any variant.
Convenience targets (eg "make coverage") are provided to retain the old
behaviour, at least for now.
See issue #3043.
