remove various code smells: - add const declarations - prefer boolean tests - don't write "for" loops without a block - don't pass non-initialized value in an array on index [0] - reduce variable scope - prefer single returns statements in functions - dont't use CONST unless defined by Tcl-API
- New macros NSF_nonnull_assert() and nonnull_assert() Background: The unreleased gcc6 with "-pedantic" complaints since recently about asserts, in which nonnull conditions implied by nonnull declarations are explicitly tested, and spits out warnings like ... warning: nonnull argument ... compared to NULL ... The new macros turns off asserts, when gcc6 is used.