Refactor python.c and fix bugs

[blueloveTH]

Fix bugs reported from @lynn

1. [BUG] Segfault when appending to a list being looped over pocketpy/pocketpy#376
2. [BUG] Associativity of if ... else pocketpy/pocketpy#377
3. [BUG] .split() should treat \t \n as whitespace pocketpy/pocketpy#378
4. [BUG] % operator only supports integers pocketpy/pocketpy#382

Refactor python.c

When tic() fails, print stack trace instead of tic_running_error!.
Fix several buggy implementations.

Changes some api

before

time() -> int
keyp(code=-1, hold=-1, period=-17) -> int
line(x0: int, y0: int, x1: int, y1: int, color: int)
pmem(index: int, value: int=None) -> int

after

time() -> float
keyp(code=-1, hold=-1, period=-17) -> bool
line(x0: float, y0: float, x1: float, y1: float, color: int)
pmem(index: int, value: int | None = None) -> int | None