Feature/add pair functors (#610)
* Move __STDC_LIMIT_MACROS and __STDC_CONSTANT_MACROS before `#include <stdint.h>`. (#601)
Macros must be defined before first include of stdint.h. Else they have no effect.
* Replace ETL_COMPILER_ICCAVR by ETL_COMPILER_IAR. (#602)
The current definition mechanism for ETL_COMPILER_ICCAVR does not work. Both IAR compilers, for ARM and AVR define `__IAR_SYSTEMS_ICC__`. Thus `ETL_COMPILER_TYPE_DETECTED` will be defined in line before ETL_COMPILER_ICCAVR is defined. This switch will never be entered.
Currently I see no reason for differentiating both compilers (`__ICCARM__` and `__ICCAVR__`). The condition for the IAR compiler platform (`__IAR_SYSTEMS_ICC__`) is sufficient (combined with <C++11 detection).
At the moment ETL_COMPILER_ICCAVR is used as a switch condition for using `#pragma push_macro`. But actually IAR ARM and IAR AVR have no such macro defined. ETL_COMPILER_IAR is defined for both compilers. Thus the switch condition is replaced with ETL_COMPILER_IAR.
* Fix 'maybe-uninitialized' g++ error on macos (#600)
* Add documentation to the pair class
* Add test directory to the EXAMPLE_PATH
* Update .gitignore
- Remove duplicate entries
- Add doxygen output directories
* Add Select1st and Select2nd functors
* Merge select1st and select2nd into utility.h
Co-authored-by: David Hebbeker <dhebbeker@users.noreply.github.com>
