Add -lm to Makefile in 1998/banks

Some systems need it to link in libm. Fedora comes to mind as an
example; macOS has no problem with it though running this entry under
macOS is another matter entirely.

1998/banks/Makefile

@@ -128,7 +128,7 @@ CFLAGS= ${CSTD} ${CWARN} ${ARCH} ${CDEFINE} ${CINCLUDE} ${OPT}
 #
 #LIBS=
 #LIBS= -lm
-LIBS= -L ${X11_LIBDIR} -lX11
+LIBS= -L ${X11_LIBDIR} -lX11 -lm
 #LIBS= -L ${HOMEBREW_PREFIX}/lib -lSDL
 
 # C compiler to use

1998/banks/README.md

@@ -16,7 +16,7 @@
 
 	cat horizon.sc pittsburgh.sc | ./banks
 
-## Judges' comments
+## Judges' comments:
 
 What can we say?  It's a flight sim done in 1536 bytes of real code.
 This one is a real marvel.  When people say the size limits are too
@@ -26,7 +26,7 @@
 The provided Makefile should work; you will need an X-ish system, and
 a select() system call.  More on building in the author comments.
 
-## Author's comments
+## Author's comments:
 
 You have just stepped out of the real world and into the
 virtual.  You are now sitting in the cockpit of a Piper Cherokee
@@ -51,30 +51,26 @@
 Features
 --------
 
-    * Simulator models a Piper Cherokee, which is a light,
+* Simulator models a Piper Cherokee, which is a light, single-engine propeller
-      single-engine propeller driven airplane.
+driven airplane.
 
-    * The airplane is modeled as a six degree-of-freedom rigid
+* The airplane is modeled as a six degree-of-freedom rigid body, accurately
-      body, accurately reflecting its dynamics (for normal flight
+reflecting its dynamics (for normal flight conditions, at least).
-      conditions, at least).
 
-    * Fly through a virtual 3-D world, while sitting at your X
+* Fly through a virtual 3-D world, while sitting at your X console.
-      console.
 
 * Loadable scenery files.
 
-    * Head-up display contains three instruments: a true airspeed
+* Head-up display contains three instruments: a true airspeed indicator, a
-      indicator, a heading indicator (compass), and an altimeter.
+heading indicator (compass), and an altimeter.
 
-    * Flight controls may be mapped to any keys at compile time
+* Flight controls may be mapped to any keys at compile time by redefining the
-      by redefining the macros in the build file.  Nice if your
+macros in the build file.  Nice if your keyboard doesn't have arrow keys.  (Or
-      keyboard doesn't have arrow keys.  (Or if you still use
+if you still use vi. :-)
-      vi. :-)
 
-    * Time step size can be set at compile time.  This is useful to
+* Time step size can be set at compile time.  This is useful to reduce flicker
-      reduce flicker on network X connections.  (But be careful:
+on network X connections.  (But be careful: step sizes longer than about 0.03
-      step sizes longer than about 0.03 seconds tend to have
+seconds tend to have numerical stability problems.)
-      numerical stability problems.)
 
 * Airplane never stalls!
 
@@ -89,7 +85,7 @@
 Scenery
 -------
 
-    Each of the *.sc files is a scenery file.  The simulator
+Each of the `*.sc` files is a scenery file.  The simulator
 program reads in the scenery from standard input on startup.
 You may input more than one scenery file, as long as there are
 less than 1000 total lines of input.
@@ -113,16 +109,20 @@
 
       river.sc      -- Follow a flowing river from the sky.
 
+
 A few examples of how to input scenery:
 
+
       cat horizon.sc pittsburgh.sc | ./banks
       cat mountains.sc bb.sc | ./banks
       cat mountains.sc river.sc pyramids.sc | ./banks
 
 You can simulate flying through a cloud bank as well:
 
+
       ./banks < /dev/null
 
+
 You will usually want at least a horizon, though.
 
 The format of scenery files is simple, by the way.  They're just
@@ -145,7 +145,7 @@
 different options.
 
 To map a key to a control, you must pass an option to the
-    compiler in the format ``-Dcontrol=key''.  The possible controls
+compiler in the format `-Dcontrol=key`.  The possible controls
 you can map are described in the table below:
 
 
@@ -161,18 +161,18 @@
 
 
 Values for the possible keys can be found in the X Windows
-    header file <X11/keysym.h>.  This file is most likely a
+header file `<X11/keysym.h>`.  This file is most likely a
-    cross-reference to another header, <X11/keysymdef.h>.
+cross-reference to another header, `<X11/keysymdef.h>`.
 
 You must map all seven controls to keys at compile time, or the
 compilation will fail.
 
 For example, to map Center Stick to the space-bar, the compile
-    option would be ``-DCS=XK_space''.
+option would be `-DCS=XK_space`.
 
 
 To set the time step size, you must pass the following option to
-    the compiler: ``-Ddt=duration'', where dt is literal, and where
+the compiler: `-Ddt=duration`, where `dt` is literal, and where
 duration is the time in seconds you want the time step to be.
 
 Two things to keep in mind when selecting a time step.  Time