Upgrade SCons to 3.0.0. re nvaccess#7520, nvaccess#7105.

Before we can move to Python 3 (nvaccess#7105), two important dependencies must be satisfied: wxPython 4 (nvaccess#7077) and SCons (nvaccess#7520). As of September 18, 2017, both were satisfied, although wxPython 4 is still in beta testing phase.
For now, upgrade SCons to 3.0.0, which supports Python 2.7, 3.5, and 3.6. Key changes include changing print statements to print function and no more Environment.gettextMoFile attribute unless it has changed somehow. Upgrading to SCons 3 is one of the prerequisites to transitioning to Python 3.x.

nvdaHelper/espeak/sconscript

@@ -77,11 +77,11 @@ def espeak_compileDict_buildAction(target,source,env):
 		lang=source[0].name.split('_')[0]
 		v=espeak_VOICE(languages=lang+'\x00')
 		if espeak.espeak_SetVoiceByProperties(ctypes.byref(v))!=0:
-			print "espeak_compileDict_action: failed to switch to language %s"%lang
+			print("espeak_compileDict_action: failed to switch to language %s"%lang)
 			return 1
 		dictPath=os.path.split(source[0].abspath)[0]+'/'
 		if espeak.espeak_ng_CompileDictionary(dictPath,None,0,None)!=0:
-			print "espeak_compileDict_action: failed to compile dictionary for  language %s"%lang
+			print("espeak_compileDict_action: failed to compile dictionary for  language %s"%lang)
 			return
 	finally:
 		espeak.espeak_Terminate()

readme.md

@@ -65,7 +65,7 @@ For reference, the following dependencies are included in Git submodules:
 * Adobe FlashAccessibility interface typelib
 * [txt2tags](http://txt2tags.sourceforge.net/), version 2.5
 * [MinHook](https://github.com/RaMMicHaeL/minhook), tagged version 1.2.2
-* [SCons](http://www.scons.org/), version 2.4.1
+* [SCons](http://www.scons.org/), version 3.0.0
 * brlapi Python bindings, version 0.5.7 or later, distributed with [BRLTTY for Windows](http://brl.thefreecat.org/brltty/), version 4.2-2
 * ALVA BC6 generic dll, version 3.0.4.1
 * lilli.dll, version 2.1.0.0

sconstruct

@@ -88,7 +88,7 @@ env.AddMethod(recursiveCopy)
 #Check for any unknown variables
 unknown=vars.UnknownVariables().keys()
 if len(unknown)>0:
-	print "Unknown commandline variables: %s"%unknown
+	print("Unknown commandline variables: %s"%unknown)
 	Exit(1)
 
 #Ensure that any Python subprocesses (such as for py2exe) can find our Python directory in miscDeps
@@ -128,7 +128,7 @@ if certPassword:
 if certTimestampServer:
 	signExecCmd.extend(("/t", certTimestampServer))
 def signExec(target,source,env):
-	print [str(x) for x in target]
+	print([str(x) for x in target])
 	#sys.exit(1)
 	# #3795: signtool can quite commonly fail with timestamping, so allow it to try up to 3 times with a 1 second delay between each try. 
 	res=0
@@ -184,8 +184,8 @@ env64.SConscript('nvdaHelper/archBuild_sconscript',exports={'env':env64,'clientI
 envWin10.SConscript('nvdaHelper/localWin10/sconscript', exports={'env': envWin10, 'libInstallDir': sourceLibDir}, variant_dir='build/x86/localWin10')
 
 #Allow all NVDA's gettext po files to be compiled in source/locale
-for po in env.Glob(sourceDir.path+'/locale/*/lc_messages/*.po'):
-	env.gettextMoFile(po)
+#for po in env.Glob(sourceDir.path+'/locale/*/lc_messages/*.po'):
+	#env.gettextMoFile(po)
 
 #Allow all key command t2t files to be generated from their userGuide t2t sources
 for lang in os.listdir(userDocsDir.path):