app-utils - simplify and move gettext wrappers

1. Instead of creating a C wrapper around gettext to then wrap in
guile, use guile's builtin gettext support directly.

The code still defines the _ and N_ shorthands. However it doesn't
really warant a separate module just for these two shorthands.
Instead define them in core-utils. So all code wanting to use
_ or N_ in guile should now use the (gnucash core-utils) module.

The bulk of this commit is actually deleting the scm-gettext
target and using (gnucash core-utils) instead of (gnucash gettext).

2. As the definition of _ and N_ is removed from app-utils.scm,
the app-utils test for a functional N_ macro has been moved to a
new test file in the guile bindinds tests.

3. The (gnucash gettext) module has been deprecated. Use
(gnucash core-utils) from now on.

bindings/guile/core-utils.scm

@@ -37,3 +37,9 @@
      (module-use! i (resolve-interface '(sw_core_utils))))
 
 (define-public gnc:version (gnc-version))
+;; gettext functions
+(define-public _ gettext)
+(define-syntax N_
+    (syntax-rules ()
+        ((_ x) x)))
+(export N_)

bindings/guile/test/CMakeLists.txt

@@ -24,7 +24,8 @@ gnc_add_test_with_guile(test-scm-query test-scm-query.cpp ENGINE_TEST_INCLUDE_DI
 # Scheme tests
 
 
-set(engine_test_SCHEME
+set(bindings_test_SCHEME
+    test-core-utils.scm
     test-create-account.scm
 )
 
@@ -33,6 +34,7 @@ set(engine_test_SCHEME
 set(GUILE_DEPENDS
     scm-gnc-module
     scm-app-utils
+    scm-core-utils
     scm-engine)
 
 gnc_add_scheme_test_targets(scm-test-engine-extras
@@ -46,7 +48,7 @@ gnc_add_scheme_test_targets(scm-test-engine-extras
 gnc_add_scheme_deprecated_module ("gnucash engine test test-extras" "tests test-engine-extras" "scm-test-engine-extras" "")
 
 gnc_add_scheme_test_targets(scm-test-engine
-    "${engine_test_SCHEME}"
+    "${bindings_test_SCHEME}"
     "tests"
     "${GUILE_DEPENDS};scm-test-engine-extras"
     FALSE
@@ -113,7 +115,7 @@ endif (HAVE_SRFI64)
 
 set(test_engine_SCHEME_DIST
     srfi64-extras.scm
-    test-create-account.scm
+    ${bindings_test_SCHEME}
     test-engine-extras.scm
     test-scm-query-import.scm
     test-business-core.scm

bindings/guile/test/test-core-utils.scm

@@ -0,0 +1,17 @@
+(define exit-code 0)
+(setenv "GNC_UNINSTALLED" "1")
+(use-modules (gnucash core-utils))
+
+(if (macro? (module-ref (current-module) 'N_))
+    (display "Macro N_ defined\n")
+    (begin
+      (display "Failed - macro N_ not defined\n")
+      (set! exit-code -1)))
+
+(if (string=? (N_ "foobar") "foobar")
+    (display "Macro N_ works properly\n")
+    (begin
+      (display "Failed - macro N_ doesn't work\n")
+      (set! exit-code -1)))
+
+(exit exit-code)