STYLE: Consistency of threadID and threadId

Comparing sources within the V4 registration code
was complicated by different use of the spelling
for local variable identifying the thread identifier.

By making this variable the same accross the toolkit,
code comparisons are made simplier and easier to keep
consistent.

Change-Id: I70bbbd2be9116c6c30472a1c93edd0b41d37b6f6
Merge topic 'Make_threadId_UseConsistent'

f32fcec8 STYLE: Consistency of threadID and threadId