Add new spacing rules pending from DML style guide

[jvsqzj]

Address pending rules tracked in issue #71

• SP.reserved: spaces around reserved words, such as if, else, default, size, const and in, except when a reserved word is used as an identifier (e.g., local uint8 *data;) - @alecalvop
• SP.binop: spaces around binary operators except the dereferencing operators dot (a.b) and arrow (a->b) - @jvsqzj
• SP.ternary: spaces around ? and : in the ternary ?: operator - @jvsqzj
• SP.ptrdecl: space between a type and the * marking a pointer - @dtarassenko
• NSP.ptrdecl: no space after the * marking a pointer in a declaration - @dtarassenko
• SP.comment: spaces around the comment delimiters //, /* and **/ - @kevv87

[jvsqzj]

There seems to be a problem with the #[serde(default)] attribute we use for LintCfg and its fields.
If one forgets to add it, then the test_example_lintcfg will pass even if the example_lintcfg.json file does not have the added rule.

We should make this clear to avoid this type of silent issues.