Merge pull request #3830 from mihails-strasuns-sociomantic/dmd-1.x

[D1] Few changes to -v2 diagnostics
Issue 13260 : ICE accessing non-existent member

Replaces assertion with an error. Does not change language
semantics but makes possible to check for presence of such
members in `is` expression.
Merge pull request #3845 from mihails-strasuns-sociomantic/fix13260-ice

[D1] Issue 13260 : ICE accessing non-existent member
fix Issue 13237 Wrong code with -inline -O

Conflicts:
	test/runnable/test23.d
fix Issue 12788 - -di doesn't warn about implicit conversion from char[] to char*
merge with D2 backend