mark some custom tex environment definitions as deprecated
mark some custom tex environment definitions as deprecated

* use `::: {.solution length=xxx} ... :::` instead of `\solutionbegin[xxx] ... \solutionend`
  => filter already working

* use `::: solution ... :::` instead of `streifenTabular` env
  => TODO filter to transform markdown tables into latex tabular needed

* `streifenMC` env will be replaced by some fenced div, too

cagix/pandoc-lecture