moved biggest stack buffers to malloc space, or made their size configurable
(8k of shell line edit buffer is an overkill)

# make ARCH=i386 bloatcheck
function                                             old     new   delta
read_line_input                                     3933    3967     +34
ifaddrlist                                           348     345      -3
do_loadfont                                          208     191     -17
edit_file                                            840     819     -21
.rodata                                           129112  129080     -32
uncompress                                          1305    1268     -37
loadfont_main                                        566     495     -71
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/6 up/down: 34/-181)          Total: -147 bytes

diff --git a/Makefile.flags b/Makefile.flags
index 988d6e7..322e437 100644
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -70,4 +70,5 @@
 #LDFLAGS += -nostdlib
 
 # Busybox is a stack-fatty so make sure we increase default size
+# (TODO: use "make stksizes" to find & fix big stack users)
 FLTFLAGS += -s 20000