doc: The fundamental concept of the grid system.
opt: Refactored the workspace css.
doc: Update.
add: Sublime project file. This will make Sublime ignore the compiled 'js' and 'css' files.
Merge branch 'master' into editor_workspace
del: Simplify the grid, row, column to only row and column. Somehow the grid's properties is the same with the row's.
opt: Extract the Dragging procedure to a separate module.
ren: Optimized the css class name.
doc: Update the specification of the grid system.
fix: Typing mistakes.
doc: Complete the definition of the grid system.
doc: Add detail.
new: Refactored the grid system.
opt: More robust.
add: Adding row prototype.
add: Underscore.string lib.
add: A modal message box function.
fix: A container that has columns inside can't hold another row.
del: Test text.