v0.4.2

SumOfSquares v0.4.2

Diff since v0.4.1

Merged pull requests:

• Monomial sparsity (#161) (@blegat)
• Fix typo in documentation (#162) (@stephentu)
• Move links from juliaopt to JuMP-dev website (#164) (@blegat)
• update URLs for jump-dev migration (#165) (@mlubin)
• Add simple SOS decomposition example (#168) (@votroto)
• Fix sparse constraints with constraint of different types (#169) (@blegat)
• Add examples in doc with Literate (#170) (@blegat)
• Allow dropping monomials in monomial sparsity (#171) (@blegat)