Revert "serializer: don't forget to reset __$a0 in opt"

This reverts commit 951a4ce48c62f6f86fd1ad887083bb155740edcf.
Revert "apply: backport applyNext behaviour fixes"

This reverts commit 38a605fbd372560ba381305b154726cf036f4497.
xjst: generate less local variables
0.4.26
Merge branch '0.4' into 0.5

Conflicts:
	lib/xjst/helpers/serializer.js
	lib/xjst/ometa/xjst.ometajs
	package.json
0.5.17