allow ghc-6.10 users to use latest vty, note vty 3.1.2 requirement for ghc <6.10

README

@@ -36,6 +36,11 @@ This will complain about any missing libraries, which you can download and
 install manually from hackage.haskell.org. (The Build-Depends: in
 hledger.cabal has the full package list.)
 
+Caveat
+......
+The current vty library requires ghc 6.10 to build, so if you are using
+ghc 6.8 you will need to use vty 3.1.2.
+
 Latest development code
 .......................
 Or, to get the latest development code do::

hledger.cabal

@@ -19,9 +19,22 @@ Extra-Tmp-Files:
 Cabal-Version:  >= 1.2
 
 Executable hledger
-  Build-Depends:  base, containers, haskell98, directory, parsec, regex-compat, regexpr>=0.5.1,
-                  old-locale, time, HUnit, vty==3.1.2, mtl, bytestring
   Main-Is:        hledger.hs
+  Build-Depends:  
+                  base,
+                  containers, 
+                  haskell98, 
+                  directory, 
+                  parsec, 
+                  regex-compat, 
+                  regexpr>=0.5.1,
+                  old-locale, 
+                  time, 
+                  HUnit, 
+                  mtl, 
+                  bytestring,
+                  -- if you have ghc <6.10 you'll need vty 3.1.2
+                  vty>=3.1.2
   Other-Modules:  
                   BalanceCommand
                   Options