We can add an integer to a Value

We have defined corresponding operators,
so rely on them to streamline the code
and increase readibility.

No functional change.
Remove some useless casts

No functional change.
Fix Intel compiler warnings

Fallout from previous patch: Intel compiler
is very noisy.

No functional change.
Don't need floor() in timeman.cpp

For positive numbers result is equivalent:
http://stackoverflow.com/questions/3300290/cast-to-int-vs-floor

Spotted by Joseph Ellis.

No functional change.
Remove other useless floor()

No functional change.