[embed] add some missing embed methods GH #829

fails with an encoding assertion in str_new_init
change extend.t: 15 extend-style compile_string + call
remove imcc/api.h from embed api test
[embed] more extend tuning, fix compile_string

use dynamic STRINGs, not constant, and not char*.
Also honor TEST_VERBOSE=2 in c_output_is
[extend] special case ext_call "->"

might be a worthwile optimization. however:
16.589294527 0.13% => 16.612686915 0.21% on parrot-bench linux
similar on darwin, but darwin bench is more noisy
[extend] remove comment for Parrot_get_root_namespace

failed bad t/codingstd/c_arg_assert.t test
ext_call: inline the strcmp
[extend] more Parrot_get_root_namespace cleanup

make headerizer.
ChangeLog line for smoke-me/embed-gh829
[codingstd] cuddled else in t/configure/034-step.t
Merge branch 'smoke-me/embed-gh829'