Minor tweaks to Start recommended by LGTM

Using the results of the vulnerability scan at lgtm.com, some minor
changes were made. First, all Python exception handling now explicitly
catches Exception, rather than BaseException (which would include SystemExit
and KeyboardInterrupt). Second, unused imports were removed. Third, a
couple of unnecessary or unused assignments were addressed. Finally, the
JavaScript was modified to explicitly declare the local ddiv variable when
needed.

src/Mod/Start/StartPage/EnableDownload.py

@@ -20,6 +20,6 @@
 #*                                                                         *
 #***************************************************************************
 
-import FreeCAD,FreeCADGui
+import FreeCAD
 rf=FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Start")
 rf.SetBool("AllowDownload",True)

src/Mod/Start/StartPage/LoadMRU.py

@@ -20,7 +20,7 @@
 #*                                                                         *
 #***************************************************************************
 
-import FreeCADGui,sys
+import FreeCADGui
 # MRU will be given before this script is run
 rf=FreeCAD.ParamGet("User parameter:BaseApp/Preferences/RecentFiles")
 FreeCADGui.loadFile(rf.GetString("MRU"+str(MRU)))

src/Mod/Start/StartPage/StartPage.js

@@ -31,7 +31,7 @@ function load() {
 
     if (allowDownloads == 1) {
         // load latest commits
-        ddiv = document.getElementById("commits");
+        var ddiv = document.getElementById("commits");
         ddiv.innerHTML = "Connecting...";
         var tobj=new JSONscriptRequest('https://api.github.com/repos/FreeCAD/FreeCAD/commits?callback=printCommits');
         tobj.buildScriptTag(); // Build the script tag
@@ -61,7 +61,7 @@ function printCommits(data) {
 
     // json callback for git commits
 
-    ddiv = document.getElementById('commits');
+    var ddiv = document.getElementById('commits');
     ddiv.innerHTML = "Received";
     var html = ['<ul>'];
     for (var i = 0; i < 25; i++) {
@@ -76,7 +76,7 @@ function printAddons(data) {
 
     // json callback for addons list
 
-    ddiv = document.getElementById('addons');
+    var ddiv = document.getElementById('addons');
     ddiv.innerHTML = "Received";
     var html = ['<ul class="addonslist">'];
     var blacklist = ['addons_installer.FCMacro','FreeCAD-Addon-Details.md','README.md'];
@@ -98,7 +98,7 @@ function printForum(data) {
 
     // json callback for forum posts
 
-    ddiv = document.getElementById('forum');
+    var ddiv = document.getElementById('forum');
     ddiv.innerHTML = "Received";
     var html = ['<ul>'];
     for (var i = 0; i < 25; i++) {

src/Mod/Start/StartPage/StartPage.py

@@ -25,7 +25,7 @@
 # the html code of the start page. It is built only once per FreeCAD session for now...
 
 import six
-import sys,os,FreeCAD,FreeCADGui,tempfile,time,zipfile,urllib,re
+import sys,os,FreeCAD,FreeCADGui,tempfile,time,zipfile,re
 from . import TranslationTexts
 from PySide import QtCore,QtGui
 
@@ -107,7 +107,7 @@ def getInfo(filename):
         try:
             import gnome.ui
             import gnomevfs
-        except:
+        except Exception:
             # alternative method
             import hashlib
             fhash = hashlib.md5(("file://"+path).encode("utf8")).hexdigest()
@@ -140,7 +140,7 @@ def getInfo(filename):
         if filename.lower().endswith(".fcstd"):
             try:
                 zfile=zipfile.ZipFile(filename)
-            except:
+            except Exception:
                 print("Cannot read file: ",filename)
                 return None
             files=zfile.namelist()
@@ -366,7 +366,6 @@ def handle():
 
     # build SECTION_RECENTFILES
 
-    SECTION_RECENTFILES = encode("")
     rf = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/RecentFiles")
     rfcount = rf.GetInt("RecentFiles",0)
     SECTION_RECENTFILES = encode("<h2>"+TranslationTexts.T_RECENTFILES+"</h2>")
@@ -493,7 +492,7 @@ def handle():
                     img = os.path.join(resources_dir,"images/freecad.png")
             iconbank[wb] = img
         UL_WORKBENCHES += '<li>'
-        UL_WORKBENCHES += '<img src="file:///'+iconbank[wb]+'">&nbsp;'
+        UL_WORKBENCHES += '<img src="file:///'+img+'">&nbsp;'
         UL_WORKBENCHES += '<a href="https://www.freecadweb.org/wiki/'+wn+'_Workbench">'+wn.replace("ReverseEngineering","ReverseEng")+'</a>'
         UL_WORKBENCHES += '</li>'
     UL_WORKBENCHES += '</ul>'
@@ -503,19 +502,19 @@ def handle():
 
     try:
         import dxfLibrary
-    except:
+    except Exception:
         pass
     else:
         wblist.append("dxf-library")
     try:
         import RebarTools
-    except:
+    except Exception:
         pass
     else:
         wblist.append("reinforcement")
     try:
         import CADExchangerIO
-    except:
+    except Exception:
         pass
     else:
         wblist.append("cadexchanger")