Build modified streamline images

The official image from streamline does not currently work for the arm64
platform. As a temporary measure, the source code and docker build scripts
have been lifted from the official images and are used to build locally.

Some additional modifications are made to reduce overall image size, these
are documented in docker/README.md

docker/streamline-src/public/elite/bootstrap/less/mixins/grid-framework.less

@@ -0,0 +1,91 @@
+// Framework grid generation
+//
+// Used only by Bootstrap to generate the correct number of grid classes given
+// any value of `@grid-columns`.
+
+.make-grid-columns() {
+  // Common styles for all sizes of grid columns, widths 1-12
+  .col(@index) { // initial
+    @item: ~".col-xs-@{index}, .col-sm-@{index}, .col-md-@{index}, .col-lg-@{index}";
+    .col((@index + 1), @item);
+  }
+  .col(@index, @list) when (@index =< @grid-columns) { // general; "=<" isn't a typo
+    @item: ~".col-xs-@{index}, .col-sm-@{index}, .col-md-@{index}, .col-lg-@{index}";
+    .col((@index + 1), ~"@{list}, @{item}");
+  }
+  .col(@index, @list) when (@index > @grid-columns) { // terminal
+    @{list} {
+      position: relative;
+      // Prevent columns from collapsing when empty
+      min-height: 1px;
+      // Inner gutter via padding
+      padding-left:  ceil((@grid-gutter-width / 2));
+      padding-right: floor((@grid-gutter-width / 2));
+    }
+  }
+  .col(1); // kickstart it
+}
+
+.float-grid-columns(@class) {
+  .col(@index) { // initial
+    @item: ~".col-@{class}-@{index}";
+    .col((@index + 1), @item);
+  }
+  .col(@index, @list) when (@index =< @grid-columns) { // general
+    @item: ~".col-@{class}-@{index}";
+    .col((@index + 1), ~"@{list}, @{item}");
+  }
+  .col(@index, @list) when (@index > @grid-columns) { // terminal
+    @{list} {
+      float: left;
+    }
+  }
+  .col(1); // kickstart it
+}
+
+.calc-grid-column(@index, @class, @type) when (@type = width) and (@index > 0) {
+  .col-@{class}-@{index} {
+    width: percentage((@index / @grid-columns));
+  }
+}
+.calc-grid-column(@index, @class, @type) when (@type = push) and (@index > 0) {
+  .col-@{class}-push-@{index} {
+    left: percentage((@index / @grid-columns));
+  }
+}
+.calc-grid-column(@index, @class, @type) when (@type = push) and (@index = 0) {
+  .col-@{class}-push-0 {
+    left: auto;
+  }
+}
+.calc-grid-column(@index, @class, @type) when (@type = pull) and (@index > 0) {
+  .col-@{class}-pull-@{index} {
+    right: percentage((@index / @grid-columns));
+  }
+}
+.calc-grid-column(@index, @class, @type) when (@type = pull) and (@index = 0) {
+  .col-@{class}-pull-0 {
+    right: auto;
+  }
+}
+.calc-grid-column(@index, @class, @type) when (@type = offset) {
+  .col-@{class}-offset-@{index} {
+    margin-left: percentage((@index / @grid-columns));
+  }
+}
+
+// Basic looping in LESS
+.loop-grid-columns(@index, @class, @type) when (@index >= 0) {
+  .calc-grid-column(@index, @class, @type);
+  // next iteration
+  .loop-grid-columns((@index - 1), @class, @type);
+}
+
+// Create grid for specific class
+.make-grid(@class) {
+  .float-grid-columns(@class);
+  .loop-grid-columns(@grid-columns, @class, width);
+  .loop-grid-columns(@grid-columns, @class, pull);
+  .loop-grid-columns(@grid-columns, @class, push);
+  .loop-grid-columns(@grid-columns, @class, offset);
+}