Merge #7920: Switch Travis to Trusty

a33b7c9 travis: temporarily disable qt to avoid timeouts (Cory Fields)
174023c travis: Don't disable writing ccache for pull-requests (Cory Fields)
cf77fcd travis: drop MAKEJOBS=2 for windows compilers (Cory Fields)
9267a47 depends: enable pre-compiled headers for qt (Cory Fields)
06fdffd travis: switch to Trusty (Cory Fields)
a6666b2 depends: mac deploy Py3 compatibility (Wladimir J. van der Laan)

contrib/macdeploy/macdeployqtplus

@@ -210,8 +210,8 @@ def getFrameworks(binaryPath, verbose):
             sys.stderr.write(o_stderr)
             sys.stderr.flush()
             raise RuntimeError("otool failed with return code %d" % otool.returncode)
-    
-    otoolLines = o_stdout.split("\n")
+
+    otoolLines = o_stdout.decode().split("\n")
     otoolLines.pop(0) # First line is the inspected binary
     if ".framework" in binaryPath or binaryPath.endswith(".dylib"):
         otoolLines.pop(0) # Frameworks and dylibs list themselves as a dependency.
@@ -676,7 +676,7 @@ if verbose >= 2:
     print("+ Installing qt.conf +")
 
 f = open(os.path.join(applicationBundle.resourcesPath, "qt.conf"), "wb")
-f.write(qt_conf)
+f.write(qt_conf.encode())
 f.close()
 
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