emu: fix flag options with defaults

Click REALLY INSISTS you provide on/off switches for your options.
You can use is_flag, but then the presence of the option changes based
on the default value.

Which makes sense, really:
@option("-f", "foobar", is_flag=True, default=False)
you would expect `./cli -f` to have `foobar is True`

whereas with
@option("-f", "foobar", is_flag=True, default=True)
you would expect `./cli -f` to have `foobar is False`, otherwise it's a
no-op

this becomes fun with `default=os.environ.get("SOMETHING")`, because
then the effect of the option CHANGES with a value of environment
variable!

there's two ways around this:
a) don't use defaults, update the flag explicitly, like:
   foobar = foobar or os.environ.get("FOOBAR") == "1"
b) forget about is_flag and specify an on/off switch, where the default
   value works as intended

since the latter is also technically speaking more correct, i'm doing it

core/emu.py

@@ -77,19 +77,23 @@ def run_debugger(emulator):
         )
 
 
+def _from_env(name):
+    return os.environ.get(name) == "1"
+
+
 @click.command(context_settings=dict(ignore_unknown_options=True))
 # fmt: off
-@click.option("-a", "--disable-animation", is_flag=True, default=os.environ.get("TREZOR_DISABLE_ANIMATION") == "1", help="Disable animation")
+@click.option("-a", "--disable-animation/--enable-animation", default=_from_env("TREZOR_DISABLE_ANIMATION"), help="Disable animation")
 @click.option("-c", "--command", "run_command", is_flag=True, help="Run command while emulator is running")
-@click.option("-d", "--production", is_flag=True, default=os.environ.get("PYOPT") == "1", help="Production mode (debuglink disabled)")
+@click.option("-d", "--production/--no-production", default=_from_env("PYOPT"), help="Production mode (debuglink disabled)")
 @click.option("-D", "--debugger", is_flag=True, help="Run emulator in debugger (gdb/lldb)")
 @click.option("--executable", type=click.Path(exists=True, dir_okay=False), default=os.environ.get("MICROPYTHON"), help="Alternate emulator executable")
-@click.option("-g", "--profiling", is_flag=True, default=os.environ.get("TREZOR_PROFILING"), help="Run with profiler wrapper")
+@click.option("-g", "--profiling/--no-profiling", default=_from_env("TREZOR_PROFILING"), help="Run with profiler wrapper")
 @click.option("-h", "--headless", is_flag=True, help="Headless mode (no display)")
 @click.option("--heap-size", metavar="SIZE", default="20M", help="Configure heap size")
 @click.option("--main", help="Path to python main file")
 @click.option("--mnemonic", "mnemonics", multiple=True, help="Initialize device with given mnemonic. Specify multiple times for Shamir shares.")
-@click.option("--log-memory", is_flag=True, default=os.environ.get("TREZOR_LOG_MEMORY") == "1", help="Print memory usage after workflows")
+@click.option("--log-memory/--no-log-memory", default=_from_env("TREZOR_LOG_MEMORY"), help="Print memory usage after workflows")
 @click.option("-o", "--output", type=click.File("w"), default="-", help="Redirect emulator output to file")
 @click.option("-p", "--profile", metavar="NAME", help="Profile name or path")
 @click.option("-P", "--port", metavar="PORT", type=int, default=int(os.environ.get("TREZOR_UDP_PORT", 0)) or None, help="UDP port number")