Merged PR 179: Fix bugs about flex and context menu (see desc) + disable hard rigid behavior + add missing properties to form + Clean up css

- Clean up some css class
- Fix wrong order when applying flex
- Fix Replace behavior not working because previous container was still existing
- Disable hard rigid behavior which disallow two container to overlap
- Add ENABLE_FLEX, ENABLE_HARD_RIGID ENABLE_SWAP
- Add missing form properties with dimensions
- Update readme

src/Components/API/api.ts

@@ -1,5 +1,4 @@
 import { IConfiguration } from '../../Interfaces/IConfiguration';
-import { IHistoryState } from '../../Interfaces/IHistoryState';
 import { ISetContainerListRequest } from '../../Interfaces/ISetContainerListRequest';
 import { ISetContainerListResponse } from '../../Interfaces/ISetContainerListResponse';
 import { GetCircularReplacer } from '../../utils/saveload';
@@ -43,6 +42,7 @@ export async function SetContainerList(request: ISetContainerListRequest): Promi
     return await fetch(url, {
       method: 'POST',
       headers: new Headers({
+        // eslint-disable-next-line @typescript-eslint/naming-convention
         'Content-Type': 'application/json'
       }),
       body: dataParsed