Truncate floats when passed to IntParameter

[mcflugen]

This pull request should fix #29.

With v0.8.0, I made a change to IntParameter whereby if it was passed a float, an error was raised. In the past, the float would have silently converted to an int. This PR makes a change so that, in such a circumstance, the floating point value is truncated and an warning is issued.

In #29, this was a problem when loading metadata from pymt_cem because it contained the following section in its parameters file,

run_duration:
  description: Simulation run time
  value:
    default: 3650.0
    range:
      max: 1.79769313486e+308
      min: 1.0
    type: int
    units: d

Notice the default is a float but the type is int.

[coveralls]

Pull Request Test Coverage Report for Build 7706479613

• -5 of 10 (50.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 73.839%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/model_metadata/model_parameter.py	5	10	50.0%
<!--	Total:	5	10	50.0%	-->

Totals
Change from base Build 7691377978:	0.2%
Covered Lines:	652
Relevant Lines:	883

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💛 - Coveralls