Add types.ts -> all types definition

src/scripts/types.ts

+export type Strand = "+" | "-";
+
+export interface GeneData {
+  eventHandler?: {
+    click: ([begin, end]: [number, number]) => void
+  },
+  name: string,
+  strand: Strand,
+  begin: number,
+  end: number,
+  gene: string,
+  fill?: string,
+  stroke?: string
+}
+export interface PositionedGeneData extends GeneData {
+  position: {
+    x: number,
+    y: number,
+    width: number
+  }
+}