added C-language ISR-wrapping macros: tn_soft_isr(vec), tn_srs_isr(vec)

For me, it is much more useful to have C-language macros instead of assembler macros, because in the case of assembler ones we have to provide separate file with list of my ISRs, so every time I change it I must change it in several places. I keep forgetting about it.

It is better if we have the way to define ISR like this:

```C
/* Timer 1 interrupt handler using software interrupt context saving */
tn_soft_isr(_TIMER_1_VECTOR)
{
   /* here is your ISR code, including clearing of interrupt flag, and so on */
}
```