He was never charged. He was questioned before he left Sweden, then after he arrived in the UK they wanted him for more questions. The difference between arrest and charge means something in Swedish law, where there isn't really a difference in the Westminster system. Being wanted for questioning isn't the same as being charged.
There were suspicions that Sweden would extradite him straight to the US, he asked for a guarantee that wouldn't happen, they refused. He offered to be interviewed in England, they refused... Until November last year, when they finally went and interviewed him in the Embassy. The case was dropped and I don't think he would be arrested if he went to Sweden, although maybe something has been said that I missed out on.
The Guardian did a timeline.
There is a lot to unpack here too. On the balance of probabilities, Russian hackers were the most likely source of the leaks. In the murky world of 'intelligence' it is very hard to sort fact from fiction, especially when the same agencies reporting on Wikileaks involvement have been subjects of previous leaks. I don't believe anyone, but if you were a leak publishing organisation and documents exposing corruption in the Democratic Party landed in your lap, would it not be your duty to publish?
Assange and Clinton also pretty clearly hate each other. I wasn't suprised that Wikileaks would go after the Democrats, it was clearly personal. Make of it what you will, but the guy has been locked in a single building for years for fear of being extradited to the US to face espionage charges. Mental health would be hard to maintain.
News organisations are political organisations.
Wikileaks are clearly not the organisation they used to be. That said, I thought supporting the human rights of a publisher who has been locked in an embassy for fear of being extradited to US because of exposing how the US operates its foreign policy would still be a cause that Pirates would at worst be ambivalent to. I am suprised that human rights means so little to so many members.  It wasn't even something we organised, it was organised by the Support Assange and Wikileaks coalition, we just tweeted the event.
This sums up my feelings on the whole thing.