[FEATURE] Add f:round, f:ceil and f:floor ViewHelpers

[s2b]

RoundViewHelper, CeilViewHelper and FloorViewHelper provide three different ways of rounding to Fluid template.

Examples

<f:round value="123.456" /> <!-- Outputs 123.46 -->
<f:ceil value="123.456" /> <!-- Outputs 124 -->
<f:floor value="123.456" /> <!-- Outputs 123 -->