Bump version number to v1.2.4

Remove use of NULL. (UCL#44)

Fixes UCL#33 .

Version 1.2.2

Update version number

Increment version no.

Modify appveyor.yml

Force cache rebuild on changes to appveyor.yml

Added STC to petpvc app (UCL#12)

fixed std::fmax in STC filter

Version 1.0.0