(core) move client code to core

Summary:
This moves all client code to core, and makes minimal fix-ups to
get grist and grist-core to compile correctly.  The client works
in core, but I'm leaving clean-up around the build and bundles to
follow-up.

Test Plan: existing tests pass; server-dev bundle looks sane

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2627

app/client/widgets/Spinner.ts

@@ -0,0 +1,32 @@
+import * as kf from 'app/client/lib/koForm';
+import {DataRowModel} from 'app/client/models/DataRowModel';
+import {ViewFieldRec} from 'app/client/models/entities/ViewFieldRec';
+import {NumericTextBox} from 'app/client/widgets/NumericTextBox';
+import {buildNumberFormat} from 'app/common/NumberFormat';
+import {dom} from 'grainjs';
+import * as ko from 'knockout';
+
+/**
+ * Spinner - A widget with a text field and spinner.
+ */
+export class Spinner extends NumericTextBox {
+  private _stepSize: ko.Computed<number>;
+
+  constructor(field: ViewFieldRec) {
+    super(field);
+    const resolved = this.autoDispose(ko.computed(() =>
+      buildNumberFormat({numMode: this.options().numMode}).resolvedOptions()));
+    this._stepSize = this.autoDispose(ko.computed(() => {
+      const extraScaling = (this.options().numMode === 'percent') ? 2 : 0;
+      return Math.pow(10, -(this.options().decimals || resolved().minimumFractionDigits) - extraScaling);
+    }));
+  }
+
+  public buildDom(row: DataRowModel) {
+    const value = row.cells[this.field.colId.peek()];
+    return dom.update(super.buildDom(row),
+      dom.cls('widget_spinner'),
+      kf.spinner(value, this._stepSize)
+    );
+  }
+}