Fix namelist incompatibility and some incompatibilities for GNU compiler in the new checks%range

[ccarouge]

PR #287 has changed the type of the range%checks entry in the cable.nml namelist, but the corresponding change in the namelist with the source code was not implemented.

In addition, the code has introduced some IF statements on integer values that will not compile with GNU compiler. These should be replaced with appropriate LOGICAL expressions.

Additionally, some non-standard line split symbols where introduced (\ instead of &).

[har917]

@ccarouge Apologies if over the top - could we also update the docs at line 130 of meteorological_forcing.md and line 159 in pft_params_nml.md just to avoid confusion in the long run