update bootstrap 4.3.1, update gulpfile, npm start script added, change SCSS file names for proper compiling

vendor/bootstrap/scss/_tables.scss

@@ -5,6 +5,7 @@
 .table {
   width: 100%;
   margin-bottom: $spacer;
+  color: $table-color;
   background-color: $table-bg; // Reset for nesting within parents with `background-color`.
 
   th,
@@ -22,10 +23,6 @@
   tbody + tbody {
     border-top: (2 * $table-border-width) solid $table-border-color;
   }
-
-  .table {
-    background-color: $body-bg;
-  }
 }
 
 
@@ -88,6 +85,7 @@
 .table-hover {
   tbody tr {
     @include hover {
+      color: $table-hover-color;
       background-color: $table-hover-bg;
     }
   }
@@ -152,6 +150,7 @@
   &.table-hover {
     tbody tr {
       @include hover {
+        color: $table-dark-hover-color;
         background-color: $table-dark-hover-bg;
       }
     }
@@ -175,7 +174,6 @@
         width: 100%;
         overflow-x: auto;
         -webkit-overflow-scrolling: touch;
-        -ms-overflow-style: -ms-autohiding-scrollbar; // See https://github.com/twbs/bootstrap/pull/10057
 
         // Prevent double border on horizontal scroll due to use of `display: block;`
         > .table-bordered {