Removed 'library' Cabal flag.

Reason: starting with Cabal 1.8, installing pandoc with '-library
+executable' did not work, since the build-depends in the Library
stanza were ignored. The problem could be solved by repeating the
build-depends in the Executable stanza, but this seems non-ideal
(and might lead to errors later on).  The '-library' option isn't
so useful anyway, since to compile pandoc in the first place, you
need a large number of Haskell libraries installed, and in this
case, why balk at another? It was chiefly intended for packagers,
but packagers will need to use a chroot environment anyway, and
they can then simply copy the executable and not the library.

Thanks to Jim Pryor for calling the problem to my attention
in connection with an arch linux package.

INSTALL

@@ -68,19 +68,19 @@ you will need [zip-archive] and (if you want syntax highlighting)
     preceded by a `-` (to force the flag to `false`), and separated
     by spaces.  Pandoc's flags include:
 
-    - `library`:  build the library (default yes)
     - `executable`: build the pandoc executable (default yes)
-    - `wrappers`: build the wrappers `markdown2pdf` and `hsmarkdown`
-      (default yes)
+    - `wrappers`: build the wrapper `markdown2pdf` (default yes)
     - `highlighting`: compile with syntax highlighting support (increases
       the size of the executable) (default no)
+    - `citeproc`: compile with bibliographic support using `citeproc-hs`
+      (default no)
 
     So, for example,
 
-        --flags="-library highlighting"
+        --flags="-executable -wrappers highlighting"
 
-    tells Cabal to build the executable but not the library, and to
-    compile with syntax highlighting support.
+    tells Cabal to build the library but not the executables,
+    and to compile with syntax highlighting support.
 
 3.  Build:
 

pandoc.cabal

@@ -131,9 +131,6 @@ Flag executable
 Flag wrappers
   Description:   Build the wrappers (markdown2pdf).
   Default:       True
-Flag library
-  Description:   Build the pandoc library.
-  Default:       True
 Flag citeproc
   Description:   Compile in support for citeproc-hs bibliographic formatting.
   Default:       False
@@ -192,11 +189,7 @@ Library
   else
     Ghc-Options:     -O2 -Wall
   Ghc-Prof-Options: -auto-all -caf-all
-
-  if flag(library)
-    Buildable:      True
-  else
-    Buildable:      False
+  Buildable:      True
 
 Executable pandoc
   Hs-Source-Dirs:     src