Support `Node.set_param(key, value)` to generate flowchart like this:
element(param1=value1,param2=value2)=>start: Start
And as a grammar sugar, support `ConditionNode.no_align_next()` to set a param `align-next=no`.
cond2(align-next=no)=>condition: Yes or No?
For convenience, you can also specify this operation when constructing a ConditionNode by:
python
ConditionNode("a cond node", align_next=False)
(Version 0.2.0 and 0.2.1 do not involve anything function of python code to flowchart, but are features regarding writing flowcharts in python.)