Misc. typos

+ some are doxy others are just comment code.  
+ some minor whitespace and grammatical tweaks. 
+ app/SCL/* typos have also been submitted upstream (https://github.com/stepcode/stepcode/pull/366). So it's ok to merge them in to master.

src/Mod/Assembly/App/opendcm/core/object.hpp

@@ -102,7 +102,7 @@ struct SignalOwner {
     * disconnect the slot by the same boost:function it was connected with.
     *
     * @tparam S the signal type of interest
-    * @param c connection with which the slot was initialy connected
+    * @param c connection with which the slot was initially connected
     * @return void
     **/
     template<typename S>

src/Mod/Assembly/App/opendcm/module3d/imp/constraint3d_holder_imp.hpp

@@ -24,7 +24,7 @@
 #include "opendcm/core/imp/constraint_holder_imp.hpp"
 
 #ifdef DCM_EXTERNAL_CORE
-//following macros are used for externalization. As the holder type can hould a very big set of combinations,
+//following macros are used for externalization. As the holder type can hold a very big set of combinations,
 //especially with module states recursive incarnation, we explicitly initiate all possible versions of this
 //struct so that it must only be compiled once. To get all possible equation
 //combinations boost pp is needed.

src/Mod/Assembly/Gui/TaskAssemblyConstraints.cpp

@@ -58,7 +58,7 @@ TaskAssemblyConstraints::TaskAssemblyConstraints(ViewProviderConstraint* vp)
     ui->setupUi(proxy);
     this->groupLayout()->addWidget(proxy);
 
-    //initialy hide the value and orientation field
+    //initially hide the value and orientation field
     ui->value_widget->hide();
     ui->orientation_widget->hide();