Unload platform def bug fix and a few small thigns

-- fixed unload bug that made a new platform type for each platform.
-- removed some unnecessary code & simplified mooring.addMooring & updated comments
-- Fixed symmetric mooring load in. Now, symmetric mooring lines have a flag added in the design dict and mooring.mirror() is called to mirror the symmetric part
-- cleaned up yaml input for shared moorings example

Author: lsirkis

examples/04_Geography/example_geography.ipynb

@@ -26,7 +26,7 @@
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+   "execution_count": null,
    "id": "3532056e",
    "metadata": {},
    "outputs": [],
@@ -46,7 +46,7 @@
   },
   {
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-   "execution_count": 113,
+   "execution_count": null,
    "id": "ae65b853",
    "metadata": {},
    "outputs": [],
@@ -68,7 +68,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 114,
+   "execution_count": null,
    "id": "c7395829",
    "metadata": {},
    "outputs": [],
@@ -92,7 +92,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 115,
+   "execution_count": null,
    "id": "4e2c6338",
    "metadata": {},
    "outputs": [],
@@ -112,7 +112,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 116,
+   "execution_count": null,
    "id": "fb432da4",
    "metadata": {},
    "outputs": [],
@@ -130,7 +130,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 117,
+   "execution_count": null,
    "id": "031f5ff7",
    "metadata": {},
    "outputs": [],
@@ -148,7 +148,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 118,
+   "execution_count": null,
    "id": "ef7a7865",
    "metadata": {},
    "outputs": [
@@ -188,7 +188,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 119,
+   "execution_count": null,
    "id": "616eaecc",
    "metadata": {},
    "outputs": [
@@ -220,7 +220,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 120,
+   "execution_count": null,
    "id": "c3b69bac",
    "metadata": {},
    "outputs": [],
@@ -250,7 +250,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 121,
+   "execution_count": null,
    "id": "fb333bc3",
    "metadata": {},
    "outputs": [],
@@ -268,7 +268,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 122,
+   "execution_count": null,
    "id": "518a9b21",
    "metadata": {},
    "outputs": [