fix a ton of bugs (2 still left as an exercise)

BUGS

@@ -0,0 +1,7 @@
+- long lines with tabs in them aren't correctly rendered when editing the part
+ outside of the boundaries of the editor windows (i.e. when scrolled to the right.)
+ a patch of dirkf exists, however it's way too intrusive, and actually doesn't even
+ work correctly.
+- if cursor is moved outside the visible bounds of a long line, the new code
+ to optimize screen redraw doesn't properly detect that the screen needs redraw
+

Makefile

@@ -1,7 +1,9 @@
+-include config.mak
+
 all: kilo
 
 kilo: kilo.c
- $(CC) -o kilo kilo.c -Wall -W -pedantic -std=c99
+ $(CC) $(CFLAGS) $(LDFLAGS) -o kilo kilo.c -Wall -W -pedantic -std=c99
 
 clean:
  rm kilo