Insertion algorithm slightly changed.

Performance boost achieved due to new insertion method.
+++++++++++++++++++++++++++++++++++++++++++++++++++
new algorithm
+++++++++++++++++++++++++++++++++++++++++++++++++++
inserting 33^2 (1089) items
watch.Elapsed {00:00:00.0365153}
watch.Elapsed {00:00:00.0387868}
watch.Elapsed {00:00:00.0383925}
inserting 33^3 (35937) items
watch.Elapsed {00:00:00.2311704}
watch.Elapsed {00:00:00.2260919}
watch.Elapsed {00:00:00.2283766}
inserting 33^4 (1185921)  items        (+ than 1 million)
watch.Elapsed {00:00:07.8308741}
watch.Elapsed {00:00:07.6420974}
watch.Elapsed {00:00:07.5651846}

+++++++++++++++++++++++++++++++++++++++++++++++++++
old algorithm
+++++++++++++++++++++++++++++++++++++++++++++++++++
inserting 33^2 (1089) items
watch.Elapsed {00:00:00.0444477}
watch.Elapsed {00:00:00.0442189}
watch.Elapsed {00:00:00.0451386}
inserting 33^3 (35937) items
watch.Elapsed {00:00:05.3035503}
watch.Elapsed {00:00:05.2693928}
inserting 33^4 (1185921) items        (+ than 1 million)
+ 50 seg