Add alex/happy as build tool dependencies, bump up unix version in gf-compiler

.gitignore

@@ -56,6 +56,12 @@ DATA_DIR
 
 stack*.yaml.lock
 
+# Generated source files
+src/compiler/api/GF/Grammar/Lexer.hs
+src/compiler/api/GF/Grammar/Parser.hs
+src/compiler/api/PackageInfo_gf.hs
+src/compiler/api/Paths_gf.hs
+
 # Output files for test suite
 *.out
 gf-tests.html

src/compiler/api/GF/Interactive.hs

@@ -39,6 +39,7 @@ import qualified Data.Sequence as Seq
 import qualified Text.ParserCombinators.ReadP as RP
 import System.Directory(getAppUserDataDirectory)
 import Control.Exception(SomeException,fromException,evaluate,try)
+import Control.Monad ((<=<),when,mplus,join)
 import Control.Monad.State hiding (void)
 import qualified GF.System.Signal as IO(runInterruptibly)
 import GF.Command.Messages(welcome)

src/compiler/gf.cabal

@@ -70,6 +70,8 @@ library
                  ghc-prim,
                  filepath, directory>=1.2, time,
                  process, haskeline, parallel>=3, json
+  build-tool-depends: alex:alex >= 3.2.4,
+                      happy:happy >= 1.19.9
   exposed-modules:
     GF.Interactive
     GF.Compiler
@@ -200,7 +202,7 @@ library
   else
     build-depends:
       terminfo >=0.4.0 && < 0.5,
-      unix >= 2.7.2 && < 2.8
+      unix >= 2.7.2 && < 2.9
 
   if flag(server)
     build-depends: