Add convenience method for getting a character's absolute position; add variant for other related methods

[JordanMartinez]

I believe we've discussed this before, but rather than typing....

int row = 4;
int col = 20;
int charPos = area.position(row, col).toOffset();

... to get the absolute position (which isn't readily obvious to new users of the code) that is necessary for other actions, for example...

area.moveTo(charPos);
area.selectRange(charPos, charPos + 2);
area.replaceText(charPos, charPos - 10, "some text")

Why not provide a convenience method that gets a character's absolute position? This would be more readably apparent than area.position(int, int).toOffset():

public int getAbsoluteCharPosition(int row, int col) { 
    return position(row, col).toOffset(); 
}

(I'm not sure if the supplied method name should be used. absoluteCharPosition might be better?)

Additionally, the above methods could be expanded to include the new row-column format:

public void moveTo(int row, int col) {
    moveTo(getAbsoluteCharPosition(startRow, startCol));
}

public void selectRange(int startRow, int startCol, int endRow, int endCol) {
    int startPos = getAbsoluteCharPosition(startRow, startCol);
    int endPos = getAbsoluteCharPosition(endRow, endCol);
    selectRange(startPos, endPos);
}


public void replaceText(int startRow, int startCol, int endRow, int endCol, String text) {
    int startPos = getAbsoluteCharPosition(startRow, startCol);
    int endPos = getAbsoluteCharPosition(endRow, endCol);
    replaceText(startPos, endPos, text);
}

[TomasMikula]

Sounds good to me.

[TomasMikula]

Resolved via #331